drm/i915/bxt: add revision id for A1 stepping and use it

[deliverable/linux.git] / drivers / gpu / drm / i915 / intel_ringbuffer.c

/*
 * Copyright © 2008-2010 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <eric@anholt.net>
 *    Zou Nan hai <nanhai.zou@intel.com>
 *    Xiang Hai hao<haihao.xiang@intel.com>
 *
 */

#include <drm/drmP.h>
#include "i915_drv.h"
#include <drm/i915_drm.h>
#include "i915_trace.h"
#include "intel_drv.h"

bool
intel_ring_initialized(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;

        if (!dev)
                return false;

        if (i915.enable_execlists) {
                struct intel_context *dctx = ring->default_context;
                struct intel_ringbuffer *ringbuf = dctx->engine[ring->id].ringbuf;

                return ringbuf->obj;
        } else
                return ring->buffer && ring->buffer->obj;
}

int __intel_ring_space(int head, int tail, int size)
{
        int space = head - tail;
        if (space <= 0)
                space += size;
        return space - I915_RING_FREE_SPACE;
}

void intel_ring_update_space(struct intel_ringbuffer *ringbuf)
{
        if (ringbuf->last_retired_head != -1) {
                ringbuf->head = ringbuf->last_retired_head;
                ringbuf->last_retired_head = -1;
        }

        ringbuf->space = __intel_ring_space(ringbuf->head & HEAD_ADDR,
                                            ringbuf->tail, ringbuf->size);
}

int intel_ring_space(struct intel_ringbuffer *ringbuf)
{
        intel_ring_update_space(ringbuf);
        return ringbuf->space;
}

bool intel_ring_stopped(struct intel_engine_cs *ring)
{
        struct drm_i915_private *dev_priv = ring->dev->dev_private;
        return dev_priv->gpu_error.stop_rings & intel_ring_flag(ring);
}

static void __intel_ring_advance(struct intel_engine_cs *ring)
{
        struct intel_ringbuffer *ringbuf = ring->buffer;
        ringbuf->tail &= ringbuf->size - 1;
        if (intel_ring_stopped(ring))
                return;
        ring->write_tail(ring, ringbuf->tail);
}

static int
gen2_render_ring_flush(struct drm_i915_gem_request *req,
                       u32      invalidate_domains,
                       u32      flush_domains)
{
        struct intel_engine_cs *ring = req->ring;
        u32 cmd;
        int ret;

        cmd = MI_FLUSH;
        if (((invalidate_domains|flush_domains) & I915_GEM_DOMAIN_RENDER) == 0)
                cmd |= MI_NO_WRITE_FLUSH;

        if (invalidate_domains & I915_GEM_DOMAIN_SAMPLER)
                cmd |= MI_READ_FLUSH;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring, cmd);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

static int
gen4_render_ring_flush(struct drm_i915_gem_request *req,
                       u32      invalidate_domains,
                       u32      flush_domains)
{
        struct intel_engine_cs *ring = req->ring;
        struct drm_device *dev = ring->dev;
        u32 cmd;
        int ret;

        /*
         * read/write caches:
         *
         * I915_GEM_DOMAIN_RENDER is always invalidated, but is
         * only flushed if MI_NO_WRITE_FLUSH is unset.  On 965, it is
         * also flushed at 2d versus 3d pipeline switches.
         *
         * read-only caches:
         *
         * I915_GEM_DOMAIN_SAMPLER is flushed on pre-965 if
         * MI_READ_FLUSH is set, and is always flushed on 965.
         *
         * I915_GEM_DOMAIN_COMMAND may not exist?
         *
         * I915_GEM_DOMAIN_INSTRUCTION, which exists on 965, is
         * invalidated when MI_EXE_FLUSH is set.
         *
         * I915_GEM_DOMAIN_VERTEX, which exists on 965, is
         * invalidated with every MI_FLUSH.
         *
         * TLBs:
         *
         * On 965, TLBs associated with I915_GEM_DOMAIN_COMMAND
         * and I915_GEM_DOMAIN_CPU in are invalidated at PTE write and
         * I915_GEM_DOMAIN_RENDER and I915_GEM_DOMAIN_SAMPLER
         * are flushed at any MI_FLUSH.
         */

        cmd = MI_FLUSH | MI_NO_WRITE_FLUSH;
        if ((invalidate_domains|flush_domains) & I915_GEM_DOMAIN_RENDER)
                cmd &= ~MI_NO_WRITE_FLUSH;
        if (invalidate_domains & I915_GEM_DOMAIN_INSTRUCTION)
                cmd |= MI_EXE_FLUSH;

        if (invalidate_domains & I915_GEM_DOMAIN_COMMAND &&
            (IS_G4X(dev) || IS_GEN5(dev)))
                cmd |= MI_INVALIDATE_ISP;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring, cmd);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

/**
 * Emits a PIPE_CONTROL with a non-zero post-sync operation, for
 * implementing two workarounds on gen6.  From section 1.4.7.1
 * "PIPE_CONTROL" of the Sandy Bridge PRM volume 2 part 1:
 *
 * [DevSNB-C+{W/A}] Before any depth stall flush (including those
 * produced by non-pipelined state commands), software needs to first
 * send a PIPE_CONTROL with no bits set except Post-Sync Operation !=
 * 0.
 *
 * [Dev-SNB{W/A}]: Before a PIPE_CONTROL with Write Cache Flush Enable
 * =1, a PIPE_CONTROL with any non-zero post-sync-op is required.
 *
 * And the workaround for these two requires this workaround first:
 *
 * [Dev-SNB{W/A}]: Pipe-control with CS-stall bit set must be sent
 * BEFORE the pipe-control with a post-sync op and no write-cache
 * flushes.
 *
 * And this last workaround is tricky because of the requirements on
 * that bit.  From section 1.4.7.2.3 "Stall" of the Sandy Bridge PRM
 * volume 2 part 1:
 *
 *     "1 of the following must also be set:
 *      - Render Target Cache Flush Enable ([12] of DW1)
 *      - Depth Cache Flush Enable ([0] of DW1)
 *      - Stall at Pixel Scoreboard ([1] of DW1)
 *      - Depth Stall ([13] of DW1)
 *      - Post-Sync Operation ([13] of DW1)
 *      - Notify Enable ([8] of DW1)"
 *
 * The cache flushes require the workaround flush that triggered this
 * one, so we can't use it.  Depth stall would trigger the same.
 * Post-sync nonzero is what triggered this second workaround, so we
 * can't use that one either.  Notify enable is IRQs, which aren't
 * really our business.  That leaves only stall at scoreboard.
 */
static int
intel_emit_post_sync_nonzero_flush(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *ring = req->ring;
        u32 scratch_addr = ring->scratch.gtt_offset + 2 * CACHELINE_BYTES;
        int ret;

        ret = intel_ring_begin(req, 6);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(5));
        intel_ring_emit(ring, PIPE_CONTROL_CS_STALL |
                        PIPE_CONTROL_STALL_AT_SCOREBOARD);
        intel_ring_emit(ring, scratch_addr | PIPE_CONTROL_GLOBAL_GTT); /* address */
        intel_ring_emit(ring, 0); /* low dword */
        intel_ring_emit(ring, 0); /* high dword */
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        ret = intel_ring_begin(req, 6);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(5));
        intel_ring_emit(ring, PIPE_CONTROL_QW_WRITE);
        intel_ring_emit(ring, scratch_addr | PIPE_CONTROL_GLOBAL_GTT); /* address */
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

static int
gen6_render_ring_flush(struct drm_i915_gem_request *req,
                       u32 invalidate_domains, u32 flush_domains)
{
        struct intel_engine_cs *ring = req->ring;
        u32 flags = 0;
        u32 scratch_addr = ring->scratch.gtt_offset + 2 * CACHELINE_BYTES;
        int ret;

        /* Force SNB workarounds for PIPE_CONTROL flushes */
        ret = intel_emit_post_sync_nonzero_flush(req);
        if (ret)
                return ret;

        /* Just flush everything.  Experiments have shown that reducing the
         * number of bits based on the write domains has little performance
         * impact.
         */
        if (flush_domains) {
                flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
                /*
                 * Ensure that any following seqno writes only happen
                 * when the render cache is indeed flushed.
                 */
                flags |= PIPE_CONTROL_CS_STALL;
        }
        if (invalidate_domains) {
                flags |= PIPE_CONTROL_TLB_INVALIDATE;
                flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
                /*
                 * TLB invalidate requires a post-sync write.
                 */
                flags |= PIPE_CONTROL_QW_WRITE | PIPE_CONTROL_CS_STALL;
        }

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(4));
        intel_ring_emit(ring, flags);
        intel_ring_emit(ring, scratch_addr | PIPE_CONTROL_GLOBAL_GTT);
        intel_ring_emit(ring, 0);
        intel_ring_advance(ring);

        return 0;
}

static int
gen7_render_ring_cs_stall_wa(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(4));
        intel_ring_emit(ring, PIPE_CONTROL_CS_STALL |
                              PIPE_CONTROL_STALL_AT_SCOREBOARD);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, 0);
        intel_ring_advance(ring);

        return 0;
}

static int
gen7_render_ring_flush(struct drm_i915_gem_request *req,
                       u32 invalidate_domains, u32 flush_domains)
{
        struct intel_engine_cs *ring = req->ring;
        u32 flags = 0;
        u32 scratch_addr = ring->scratch.gtt_offset + 2 * CACHELINE_BYTES;
        int ret;

        /*
         * Ensure that any following seqno writes only happen when the render
         * cache is indeed flushed.
         *
         * Workaround: 4th PIPE_CONTROL command (except the ones with only
         * read-cache invalidate bits set) must have the CS_STALL bit set. We
         * don't try to be clever and just set it unconditionally.
         */
        flags |= PIPE_CONTROL_CS_STALL;

        /* Just flush everything.  Experiments have shown that reducing the
         * number of bits based on the write domains has little performance
         * impact.
         */
        if (flush_domains) {
                flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
        }
        if (invalidate_domains) {
                flags |= PIPE_CONTROL_TLB_INVALIDATE;
                flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_MEDIA_STATE_CLEAR;
                /*
                 * TLB invalidate requires a post-sync write.
                 */
                flags |= PIPE_CONTROL_QW_WRITE;
                flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;

                flags |= PIPE_CONTROL_STALL_AT_SCOREBOARD;

                /* Workaround: we must issue a pipe_control with CS-stall bit
                 * set before a pipe_control command that has the state cache
                 * invalidate bit set. */
                gen7_render_ring_cs_stall_wa(req);
        }

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(4));
        intel_ring_emit(ring, flags);
        intel_ring_emit(ring, scratch_addr);
        intel_ring_emit(ring, 0);
        intel_ring_advance(ring);

        return 0;
}

static int
gen8_emit_pipe_control(struct drm_i915_gem_request *req,
                       u32 flags, u32 scratch_addr)
{
        struct intel_engine_cs *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 6);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(6));
        intel_ring_emit(ring, flags);
        intel_ring_emit(ring, scratch_addr);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, 0);
        intel_ring_advance(ring);

        return 0;
}

static int
gen8_render_ring_flush(struct drm_i915_gem_request *req,
                       u32 invalidate_domains, u32 flush_domains)
{
        u32 flags = 0;
        u32 scratch_addr = req->ring->scratch.gtt_offset + 2 * CACHELINE_BYTES;
        int ret;

        flags |= PIPE_CONTROL_CS_STALL;

        if (flush_domains) {
                flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
        }
        if (invalidate_domains) {
                flags |= PIPE_CONTROL_TLB_INVALIDATE;
                flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_QW_WRITE;
                flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;

                /* WaCsStallBeforeStateCacheInvalidate:bdw,chv */
                ret = gen8_emit_pipe_control(req,
                                             PIPE_CONTROL_CS_STALL |
                                             PIPE_CONTROL_STALL_AT_SCOREBOARD,
                                             0);
                if (ret)
                        return ret;
        }

        return gen8_emit_pipe_control(req, flags, scratch_addr);
}

static void ring_write_tail(struct intel_engine_cs *ring,
                            u32 value)
{
        struct drm_i915_private *dev_priv = ring->dev->dev_private;
        I915_WRITE_TAIL(ring, value);
}

u64 intel_ring_get_active_head(struct intel_engine_cs *ring)
{
        struct drm_i915_private *dev_priv = ring->dev->dev_private;
        u64 acthd;

        if (INTEL_INFO(ring->dev)->gen >= 8)
                acthd = I915_READ64_2x32(RING_ACTHD(ring->mmio_base),
                                         RING_ACTHD_UDW(ring->mmio_base));
        else if (INTEL_INFO(ring->dev)->gen >= 4)
                acthd = I915_READ(RING_ACTHD(ring->mmio_base));
        else
                acthd = I915_READ(ACTHD);

        return acthd;
}

static void ring_setup_phys_status_page(struct intel_engine_cs *ring)
{
        struct drm_i915_private *dev_priv = ring->dev->dev_private;
        u32 addr;

        addr = dev_priv->status_page_dmah->busaddr;
        if (INTEL_INFO(ring->dev)->gen >= 4)
                addr |= (dev_priv->status_page_dmah->busaddr >> 28) & 0xf0;
        I915_WRITE(HWS_PGA, addr);
}

static void intel_ring_setup_status_page(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = ring->dev->dev_private;
        u32 mmio = 0;

        /* The ring status page addresses are no longer next to the rest of
         * the ring registers as of gen7.
         */
        if (IS_GEN7(dev)) {
                switch (ring->id) {
                case RCS:
                        mmio = RENDER_HWS_PGA_GEN7;
                        break;
                case BCS:
                        mmio = BLT_HWS_PGA_GEN7;
                        break;
                /*
                 * VCS2 actually doesn't exist on Gen7. Only shut up
                 * gcc switch check warning
                 */
                case VCS2:
                case VCS:
                        mmio = BSD_HWS_PGA_GEN7;
                        break;
                case VECS:
                        mmio = VEBOX_HWS_PGA_GEN7;
                        break;
                }
        } else if (IS_GEN6(ring->dev)) {
                mmio = RING_HWS_PGA_GEN6(ring->mmio_base);
        } else {
                /* XXX: gen8 returns to sanity */
                mmio = RING_HWS_PGA(ring->mmio_base);
        }

        I915_WRITE(mmio, (u32)ring->status_page.gfx_addr);
        POSTING_READ(mmio);

        /*
         * Flush the TLB for this page
         *
         * FIXME: These two bits have disappeared on gen8, so a question
         * arises: do we still need this and if so how should we go about
         * invalidating the TLB?
         */
        if (INTEL_INFO(dev)->gen >= 6 && INTEL_INFO(dev)->gen < 8) {
                u32 reg = RING_INSTPM(ring->mmio_base);

                /* ring should be idle before issuing a sync flush*/
                WARN_ON((I915_READ_MODE(ring) & MODE_IDLE) == 0);

                I915_WRITE(reg,
                           _MASKED_BIT_ENABLE(INSTPM_TLB_INVALIDATE |
                                              INSTPM_SYNC_FLUSH));
                if (wait_for((I915_READ(reg) & INSTPM_SYNC_FLUSH) == 0,
                             1000))
                        DRM_ERROR("%s: wait for SyncFlush to complete for TLB invalidation timed out\n",
                                  ring->name);
        }
}

static bool stop_ring(struct intel_engine_cs *ring)
{
        struct drm_i915_private *dev_priv = to_i915(ring->dev);

        if (!IS_GEN2(ring->dev)) {
                I915_WRITE_MODE(ring, _MASKED_BIT_ENABLE(STOP_RING));
                if (wait_for((I915_READ_MODE(ring) & MODE_IDLE) != 0, 1000)) {
                        DRM_ERROR("%s : timed out trying to stop ring\n", ring->name);
                        /* Sometimes we observe that the idle flag is not
                         * set even though the ring is empty. So double
                         * check before giving up.
                         */
                        if (I915_READ_HEAD(ring) != I915_READ_TAIL(ring))
                                return false;
                }
        }

        I915_WRITE_CTL(ring, 0);
        I915_WRITE_HEAD(ring, 0);
        ring->write_tail(ring, 0);

        if (!IS_GEN2(ring->dev)) {
                (void)I915_READ_CTL(ring);
                I915_WRITE_MODE(ring, _MASKED_BIT_DISABLE(STOP_RING));
        }

        return (I915_READ_HEAD(ring) & HEAD_ADDR) == 0;
}

static int init_ring_common(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_ringbuffer *ringbuf = ring->buffer;
        struct drm_i915_gem_object *obj = ringbuf->obj;
        int ret = 0;

        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

        if (!stop_ring(ring)) {
                /* G45 ring initialization often fails to reset head to zero */
                DRM_DEBUG_KMS("%s head not reset to zero "
                              "ctl %08x head %08x tail %08x start %08x\n",
                              ring->name,
                              I915_READ_CTL(ring),
                              I915_READ_HEAD(ring),
                              I915_READ_TAIL(ring),
                              I915_READ_START(ring));

                if (!stop_ring(ring)) {
                        DRM_ERROR("failed to set %s head to zero "
                                  "ctl %08x head %08x tail %08x start %08x\n",
                                  ring->name,
                                  I915_READ_CTL(ring),
                                  I915_READ_HEAD(ring),
                                  I915_READ_TAIL(ring),
                                  I915_READ_START(ring));
                        ret = -EIO;
                        goto out;
                }
        }

        if (I915_NEED_GFX_HWS(dev))
                intel_ring_setup_status_page(ring);
        else
                ring_setup_phys_status_page(ring);

        /* Enforce ordering by reading HEAD register back */
        I915_READ_HEAD(ring);

        /* Initialize the ring. This must happen _after_ we've cleared the ring
         * registers with the above sequence (the readback of the HEAD registers
         * also enforces ordering), otherwise the hw might lose the new ring
         * register values. */
        I915_WRITE_START(ring, i915_gem_obj_ggtt_offset(obj));

        /* WaClearRingBufHeadRegAtInit:ctg,elk */
        if (I915_READ_HEAD(ring))
                DRM_DEBUG("%s initialization failed [head=%08x], fudging\n",
                          ring->name, I915_READ_HEAD(ring));
        I915_WRITE_HEAD(ring, 0);
        (void)I915_READ_HEAD(ring);

        I915_WRITE_CTL(ring,
                        ((ringbuf->size - PAGE_SIZE) & RING_NR_PAGES)
                        | RING_VALID);

        /* If the head is still not zero, the ring is dead */
        if (wait_for((I915_READ_CTL(ring) & RING_VALID) != 0 &&
                     I915_READ_START(ring) == i915_gem_obj_ggtt_offset(obj) &&
                     (I915_READ_HEAD(ring) & HEAD_ADDR) == 0, 50)) {
                DRM_ERROR("%s initialization failed "
                          "ctl %08x (valid? %d) head %08x tail %08x start %08x [expected %08lx]\n",
                          ring->name,
                          I915_READ_CTL(ring), I915_READ_CTL(ring) & RING_VALID,
                          I915_READ_HEAD(ring), I915_READ_TAIL(ring),
                          I915_READ_START(ring), (unsigned long)i915_gem_obj_ggtt_offset(obj));
                ret = -EIO;
                goto out;
        }

        ringbuf->last_retired_head = -1;
        ringbuf->head = I915_READ_HEAD(ring);
        ringbuf->tail = I915_READ_TAIL(ring) & TAIL_ADDR;
        intel_ring_update_space(ringbuf);

        memset(&ring->hangcheck, 0, sizeof(ring->hangcheck));

out:
        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);

        return ret;
}

void
intel_fini_pipe_control(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;

        if (ring->scratch.obj == NULL)
                return;

        if (INTEL_INFO(dev)->gen >= 5) {
                kunmap(sg_page(ring->scratch.obj->pages->sgl));
                i915_gem_object_ggtt_unpin(ring->scratch.obj);
        }

        drm_gem_object_unreference(&ring->scratch.obj->base);
        ring->scratch.obj = NULL;
}

int
intel_init_pipe_control(struct intel_engine_cs *ring)
{
        int ret;

        WARN_ON(ring->scratch.obj);

        ring->scratch.obj = i915_gem_alloc_object(ring->dev, 4096);
        if (ring->scratch.obj == NULL) {
                DRM_ERROR("Failed to allocate seqno page\n");
                ret = -ENOMEM;
                goto err;
        }

        ret = i915_gem_object_set_cache_level(ring->scratch.obj, I915_CACHE_LLC);
        if (ret)
                goto err_unref;

        ret = i915_gem_obj_ggtt_pin(ring->scratch.obj, 4096, 0);
        if (ret)
                goto err_unref;

        ring->scratch.gtt_offset = i915_gem_obj_ggtt_offset(ring->scratch.obj);
        ring->scratch.cpu_page = kmap(sg_page(ring->scratch.obj->pages->sgl));
        if (ring->scratch.cpu_page == NULL) {
                ret = -ENOMEM;
                goto err_unpin;
        }

        DRM_DEBUG_DRIVER("%s pipe control offset: 0x%08x\n",
                         ring->name, ring->scratch.gtt_offset);
        return 0;

err_unpin:
        i915_gem_object_ggtt_unpin(ring->scratch.obj);
err_unref:
        drm_gem_object_unreference(&ring->scratch.obj->base);
err:
        return ret;
}

static int intel_ring_workarounds_emit(struct drm_i915_gem_request *req)
{
        int ret, i;
        struct intel_engine_cs *ring = req->ring;
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct i915_workarounds *w = &dev_priv->workarounds;

        if (w->count == 0)
                return 0;

        ring->gpu_caches_dirty = true;
        ret = intel_ring_flush_all_caches(req);
        if (ret)
                return ret;

        ret = intel_ring_begin(req, (w->count * 2 + 2));
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(w->count));
        for (i = 0; i < w->count; i++) {
                intel_ring_emit(ring, w->reg[i].addr);
                intel_ring_emit(ring, w->reg[i].value);
        }
        intel_ring_emit(ring, MI_NOOP);

        intel_ring_advance(ring);

        ring->gpu_caches_dirty = true;
        ret = intel_ring_flush_all_caches(req);
        if (ret)
                return ret;

        DRM_DEBUG_DRIVER("Number of Workarounds emitted: %d\n", w->count);

        return 0;
}

static int intel_rcs_ctx_init(struct drm_i915_gem_request *req)
{
        int ret;

        ret = intel_ring_workarounds_emit(req);
        if (ret != 0)
                return ret;

        ret = i915_gem_render_state_init(req);
        if (ret)
                DRM_ERROR("init render state: %d\n", ret);

        return ret;
}

static int wa_add(struct drm_i915_private *dev_priv,
                  const u32 addr, const u32 mask, const u32 val)
{
        const u32 idx = dev_priv->workarounds.count;

        if (WARN_ON(idx >= I915_MAX_WA_REGS))
                return -ENOSPC;

        dev_priv->workarounds.reg[idx].addr = addr;
        dev_priv->workarounds.reg[idx].value = val;
        dev_priv->workarounds.reg[idx].mask = mask;

        dev_priv->workarounds.count++;

        return 0;
}

#define WA_REG(addr, mask, val) do { \
                const int r = wa_add(dev_priv, (addr), (mask), (val)); \
                if (r) \
                        return r; \
        } while (0)

#define WA_SET_BIT_MASKED(addr, mask) \
        WA_REG(addr, (mask), _MASKED_BIT_ENABLE(mask))

#define WA_CLR_BIT_MASKED(addr, mask) \
        WA_REG(addr, (mask), _MASKED_BIT_DISABLE(mask))

#define WA_SET_FIELD_MASKED(addr, mask, value) \
        WA_REG(addr, mask, _MASKED_FIELD(mask, value))

#define WA_SET_BIT(addr, mask) WA_REG(addr, mask, I915_READ(addr) | (mask))
#define WA_CLR_BIT(addr, mask) WA_REG(addr, mask, I915_READ(addr) & ~(mask))

#define WA_WRITE(addr, val) WA_REG(addr, 0xffffffff, val)

static int gen8_init_workarounds(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        WA_SET_BIT_MASKED(INSTPM, INSTPM_FORCE_ORDERING);

        /* WaDisableAsyncFlipPerfMode:bdw,chv */
        WA_SET_BIT_MASKED(MI_MODE, ASYNC_FLIP_PERF_DISABLE);

        /* WaDisablePartialInstShootdown:bdw,chv */
        WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
                          PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE);

        /* Use Force Non-Coherent whenever executing a 3D context. This is a
         * workaround for for a possible hang in the unlikely event a TLB
         * invalidation occurs during a PSD flush.
         */
        /* WaForceEnableNonCoherent:bdw,chv */
        /* WaHdcDisableFetchWhenMasked:bdw,chv */
        WA_SET_BIT_MASKED(HDC_CHICKEN0,
                          HDC_DONOT_FETCH_MEM_WHEN_MASKED |
                          HDC_FORCE_NON_COHERENT);

        /* From the Haswell PRM, Command Reference: Registers, CACHE_MODE_0:
         * "The Hierarchical Z RAW Stall Optimization allows non-overlapping
         *  polygons in the same 8x4 pixel/sample area to be processed without
         *  stalling waiting for the earlier ones to write to Hierarchical Z
         *  buffer."
         *
         * This optimization is off by default for BDW and CHV; turn it on.
         */
        WA_CLR_BIT_MASKED(CACHE_MODE_0_GEN7, HIZ_RAW_STALL_OPT_DISABLE);

        /* Wa4x4STCOptimizationDisable:bdw,chv */
        WA_SET_BIT_MASKED(CACHE_MODE_1, GEN8_4x4_STC_OPTIMIZATION_DISABLE);

        /*
         * BSpec recommends 8x4 when MSAA is used,
         * however in practice 16x4 seems fastest.
         *
         * Note that PS/WM thread counts depend on the WIZ hashing
         * disable bit, which we don't touch here, but it's good
         * to keep in mind (see 3DSTATE_PS and 3DSTATE_WM).
         */
        WA_SET_FIELD_MASKED(GEN7_GT_MODE,
                            GEN6_WIZ_HASHING_MASK,
                            GEN6_WIZ_HASHING_16x4);

        return 0;
}

static int bdw_init_workarounds(struct intel_engine_cs *ring)
{
        int ret;
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        ret = gen8_init_workarounds(ring);
        if (ret)
                return ret;

        /* WaDisableThreadStallDopClockGating:bdw (pre-production) */
        WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN, STALL_DOP_GATING_DISABLE);

        /* WaDisableDopClockGating:bdw */
        WA_SET_BIT_MASKED(GEN7_ROW_CHICKEN2,
                          DOP_CLOCK_GATING_DISABLE);

        WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN3,
                          GEN8_SAMPLER_POWER_BYPASS_DIS);

        WA_SET_BIT_MASKED(HDC_CHICKEN0,
                          /* WaForceContextSaveRestoreNonCoherent:bdw */
                          HDC_FORCE_CONTEXT_SAVE_RESTORE_NON_COHERENT |
                          /* WaDisableFenceDestinationToSLM:bdw (pre-prod) */
                          (IS_BDW_GT3(dev) ? HDC_FENCE_DEST_SLM_DISABLE : 0));

        return 0;
}

static int chv_init_workarounds(struct intel_engine_cs *ring)
{
        int ret;
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        ret = gen8_init_workarounds(ring);
        if (ret)
                return ret;

        /* WaDisableThreadStallDopClockGating:chv */
        WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN, STALL_DOP_GATING_DISABLE);

        /* Improve HiZ throughput on CHV. */
        WA_SET_BIT_MASKED(HIZ_CHICKEN, CHV_HZ_8X8_MODE_IN_1X);

        return 0;
}

static int gen9_init_workarounds(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        uint32_t tmp;

        /* WaEnableLbsSlaRetryTimerDecrement:skl */
        I915_WRITE(BDW_SCRATCH1, I915_READ(BDW_SCRATCH1) |
                   GEN9_LBS_SLA_RETRY_TIMER_DECREMENT_ENABLE);

        /* WaDisableKillLogic:bxt,skl */
        I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) |
                   ECOCHK_DIS_TLB);

        /* WaDisablePartialInstShootdown:skl,bxt */
        WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
                          PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE);

        /* Syncing dependencies between camera and graphics:skl,bxt */
        WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN3,
                          GEN9_DISABLE_OCL_OOB_SUPPRESS_LOGIC);

        if ((IS_SKYLAKE(dev) && (INTEL_REVID(dev) == SKL_REVID_A0 ||
            INTEL_REVID(dev) == SKL_REVID_B0)) ||
            (IS_BROXTON(dev) && INTEL_REVID(dev) <= BXT_REVID_A1)) {
                /* WaDisableDgMirrorFixInHalfSliceChicken5:skl,bxt */
                WA_CLR_BIT_MASKED(GEN9_HALF_SLICE_CHICKEN5,
                                  GEN9_DG_MIRROR_FIX_ENABLE);
        }

        if ((IS_SKYLAKE(dev) && INTEL_REVID(dev) <= SKL_REVID_B0) ||
            (IS_BROXTON(dev) && INTEL_REVID(dev) <= BXT_REVID_A1)) {
                /* WaSetDisablePixMaskCammingAndRhwoInCommonSliceChicken:skl,bxt */
                WA_SET_BIT_MASKED(GEN7_COMMON_SLICE_CHICKEN1,
                                  GEN9_RHWO_OPTIMIZATION_DISABLE);
                /*
                 * WA also requires GEN9_SLICE_COMMON_ECO_CHICKEN0[14:14] to be set
                 * but we do that in per ctx batchbuffer as there is an issue
                 * with this register not getting restored on ctx restore
                 */
        }

        if ((IS_SKYLAKE(dev) && INTEL_REVID(dev) >= SKL_REVID_C0) ||
            IS_BROXTON(dev)) {
                /* WaEnableYV12BugFixInHalfSliceChicken7:skl,bxt */
                WA_SET_BIT_MASKED(GEN9_HALF_SLICE_CHICKEN7,
                                  GEN9_ENABLE_YV12_BUGFIX);
        }

        /* Wa4x4STCOptimizationDisable:skl,bxt */
        /* WaDisablePartialResolveInVc:skl,bxt */
        WA_SET_BIT_MASKED(CACHE_MODE_1, (GEN8_4x4_STC_OPTIMIZATION_DISABLE |
                                         GEN9_PARTIAL_RESOLVE_IN_VC_DISABLE));

        /* WaCcsTlbPrefetchDisable:skl,bxt */
        WA_CLR_BIT_MASKED(GEN9_HALF_SLICE_CHICKEN5,
                          GEN9_CCS_TLB_PREFETCH_ENABLE);

        /* WaDisableMaskBasedCammingInRCC:skl,bxt */
        if ((IS_SKYLAKE(dev) && INTEL_REVID(dev) == SKL_REVID_C0) ||
            (IS_BROXTON(dev) && INTEL_REVID(dev) <= BXT_REVID_A1))
                WA_SET_BIT_MASKED(SLICE_ECO_CHICKEN0,
                                  PIXEL_MASK_CAMMING_DISABLE);

        /* WaForceContextSaveRestoreNonCoherent:skl,bxt */
        tmp = HDC_FORCE_CONTEXT_SAVE_RESTORE_NON_COHERENT;
        if ((IS_SKYLAKE(dev) && INTEL_REVID(dev) == SKL_REVID_F0) ||
            (IS_BROXTON(dev) && INTEL_REVID(dev) >= BXT_REVID_B0))
                tmp |= HDC_FORCE_CSR_NON_COHERENT_OVR_DISABLE;
        WA_SET_BIT_MASKED(HDC_CHICKEN0, tmp);

        /* WaDisableSamplerPowerBypassForSOPingPong:skl,bxt */
        if (IS_SKYLAKE(dev) ||
            (IS_BROXTON(dev) && INTEL_REVID(dev) <= BXT_REVID_B0)) {
                WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN3,
                                  GEN8_SAMPLER_POWER_BYPASS_DIS);
        }

        /* WaDisableSTUnitPowerOptimization:skl,bxt */
        WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN2, GEN8_ST_PO_DISABLE);

        return 0;
}

static int skl_tune_iz_hashing(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        u8 vals[3] = { 0, 0, 0 };
        unsigned int i;

        for (i = 0; i < 3; i++) {
                u8 ss;

                /*
                 * Only consider slices where one, and only one, subslice has 7
                 * EUs
                 */
                if (hweight8(dev_priv->info.subslice_7eu[i]) != 1)
                        continue;

                /*
                 * subslice_7eu[i] != 0 (because of the check above) and
                 * ss_max == 4 (maximum number of subslices possible per slice)
                 *
                 * ->    0 <= ss <= 3;
                 */
                ss = ffs(dev_priv->info.subslice_7eu[i]) - 1;
                vals[i] = 3 - ss;
        }

        if (vals[0] == 0 && vals[1] == 0 && vals[2] == 0)
                return 0;

        /* Tune IZ hashing. See intel_device_info_runtime_init() */
        WA_SET_FIELD_MASKED(GEN7_GT_MODE,
                            GEN9_IZ_HASHING_MASK(2) |
                            GEN9_IZ_HASHING_MASK(1) |
                            GEN9_IZ_HASHING_MASK(0),
                            GEN9_IZ_HASHING(2, vals[2]) |
                            GEN9_IZ_HASHING(1, vals[1]) |
                            GEN9_IZ_HASHING(0, vals[0]));

        return 0;
}

static int skl_init_workarounds(struct intel_engine_cs *ring)
{
        int ret;
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        ret = gen9_init_workarounds(ring);
        if (ret)
                return ret;

        if (INTEL_REVID(dev) <= SKL_REVID_D0) {
                /* WaDisableHDCInvalidation:skl */
                I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) |
                           BDW_DISABLE_HDC_INVALIDATION);

                /* WaDisableChickenBitTSGBarrierAckForFFSliceCS:skl */
                I915_WRITE(FF_SLICE_CS_CHICKEN2,
                           _MASKED_BIT_ENABLE(GEN9_TSG_BARRIER_ACK_DISABLE));
        }

        /* GEN8_L3SQCREG4 has a dependency with WA batch so any new changes
         * involving this register should also be added to WA batch as required.
         */
        if (INTEL_REVID(dev) <= SKL_REVID_E0)
                /* WaDisableLSQCROPERFforOCL:skl */
                I915_WRITE(GEN8_L3SQCREG4, I915_READ(GEN8_L3SQCREG4) |
                           GEN8_LQSC_RO_PERF_DIS);

        /* WaEnableGapsTsvCreditFix:skl */
        if (IS_SKYLAKE(dev) && (INTEL_REVID(dev) >= SKL_REVID_C0)) {
                I915_WRITE(GEN8_GARBCNTL, (I915_READ(GEN8_GARBCNTL) |
                                           GEN9_GAPS_TSV_CREDIT_DISABLE));
        }

        /* WaDisablePowerCompilerClockGating:skl */
        if (INTEL_REVID(dev) == SKL_REVID_B0)
                WA_SET_BIT_MASKED(HIZ_CHICKEN,
                                  BDW_HIZ_POWER_COMPILER_CLOCK_GATING_DISABLE);

        if (INTEL_REVID(dev) <= SKL_REVID_D0) {
                /*
                 *Use Force Non-Coherent whenever executing a 3D context. This
                 * is a workaround for a possible hang in the unlikely event
                 * a TLB invalidation occurs during a PSD flush.
                 */
                /* WaForceEnableNonCoherent:skl */
                WA_SET_BIT_MASKED(HDC_CHICKEN0,
                                  HDC_FORCE_NON_COHERENT);
        }

        if (INTEL_REVID(dev) == SKL_REVID_C0 ||
            INTEL_REVID(dev) == SKL_REVID_D0)
                /* WaBarrierPerformanceFixDisable:skl */
                WA_SET_BIT_MASKED(HDC_CHICKEN0,
                                  HDC_FENCE_DEST_SLM_DISABLE |
                                  HDC_BARRIER_PERFORMANCE_DISABLE);

        /* WaDisableSbeCacheDispatchPortSharing:skl */
        if (INTEL_REVID(dev) <= SKL_REVID_F0) {
                WA_SET_BIT_MASKED(
                        GEN7_HALF_SLICE_CHICKEN1,
                        GEN7_SBE_SS_CACHE_DISPATCH_PORT_SHARING_DISABLE);
        }

        return skl_tune_iz_hashing(ring);
}

static int bxt_init_workarounds(struct intel_engine_cs *ring)
{
        int ret;
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        ret = gen9_init_workarounds(ring);
        if (ret)
                return ret;

        /* WaStoreMultiplePTEenable:bxt */
        /* This is a requirement according to Hardware specification */
        if (INTEL_REVID(dev) == BXT_REVID_A0)
                I915_WRITE(TILECTL, I915_READ(TILECTL) | TILECTL_TLBPF);

        /* WaSetClckGatingDisableMedia:bxt */
        if (INTEL_REVID(dev) == BXT_REVID_A0) {
                I915_WRITE(GEN7_MISCCPCTL, (I915_READ(GEN7_MISCCPCTL) &
                                            ~GEN8_DOP_CLOCK_GATE_MEDIA_ENABLE));
        }

        /* WaDisableThreadStallDopClockGating:bxt */
        WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
                          STALL_DOP_GATING_DISABLE);

        /* WaDisableSbeCacheDispatchPortSharing:bxt */
        if (INTEL_REVID(dev) <= BXT_REVID_B0) {
                WA_SET_BIT_MASKED(
                        GEN7_HALF_SLICE_CHICKEN1,
                        GEN7_SBE_SS_CACHE_DISPATCH_PORT_SHARING_DISABLE);
        }

        return 0;
}

int init_workarounds_ring(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        WARN_ON(ring->id != RCS);

        dev_priv->workarounds.count = 0;

        if (IS_BROADWELL(dev))
                return bdw_init_workarounds(ring);

        if (IS_CHERRYVIEW(dev))
                return chv_init_workarounds(ring);

        if (IS_SKYLAKE(dev))
                return skl_init_workarounds(ring);

        if (IS_BROXTON(dev))
                return bxt_init_workarounds(ring);

        return 0;
}

static int init_render_ring(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        int ret = init_ring_common(ring);
        if (ret)
                return ret;

        /* WaTimedSingleVertexDispatch:cl,bw,ctg,elk,ilk,snb */
        if (INTEL_INFO(dev)->gen >= 4 && INTEL_INFO(dev)->gen < 7)
                I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(VS_TIMER_DISPATCH));

        /* We need to disable the AsyncFlip performance optimisations in order
         * to use MI_WAIT_FOR_EVENT within the CS. It should already be
         * programmed to '1' on all products.
         *
         * WaDisableAsyncFlipPerfMode:snb,ivb,hsw,vlv
         */
        if (INTEL_INFO(dev)->gen >= 6 && INTEL_INFO(dev)->gen < 8)
                I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(ASYNC_FLIP_PERF_DISABLE));

        /* Required for the hardware to program scanline values for waiting */
        /* WaEnableFlushTlbInvalidationMode:snb */
        if (INTEL_INFO(dev)->gen == 6)
                I915_WRITE(GFX_MODE,
                           _MASKED_BIT_ENABLE(GFX_TLB_INVALIDATE_EXPLICIT));

        /* WaBCSVCSTlbInvalidationMode:ivb,vlv,hsw */
        if (IS_GEN7(dev))
                I915_WRITE(GFX_MODE_GEN7,
                           _MASKED_BIT_ENABLE(GFX_TLB_INVALIDATE_EXPLICIT) |
                           _MASKED_BIT_ENABLE(GFX_REPLAY_MODE));

        if (IS_GEN6(dev)) {
                /* From the Sandybridge PRM, volume 1 part 3, page 24:
                 * "If this bit is set, STCunit will have LRA as replacement
                 *  policy. [...] This bit must be reset.  LRA replacement
                 *  policy is not supported."
                 */
                I915_WRITE(CACHE_MODE_0,
                           _MASKED_BIT_DISABLE(CM0_STC_EVICT_DISABLE_LRA_SNB));
        }

        if (INTEL_INFO(dev)->gen >= 6 && INTEL_INFO(dev)->gen < 8)
                I915_WRITE(INSTPM, _MASKED_BIT_ENABLE(INSTPM_FORCE_ORDERING));

        if (HAS_L3_DPF(dev))
                I915_WRITE_IMR(ring, ~GT_PARITY_ERROR(dev));

        return init_workarounds_ring(ring);
}

static void render_ring_cleanup(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        if (dev_priv->semaphore_obj) {
                i915_gem_object_ggtt_unpin(dev_priv->semaphore_obj);
                drm_gem_object_unreference(&dev_priv->semaphore_obj->base);
                dev_priv->semaphore_obj = NULL;
        }

        intel_fini_pipe_control(ring);
}

static int gen8_rcs_signal(struct drm_i915_gem_request *signaller_req,
                           unsigned int num_dwords)
{
#define MBOX_UPDATE_DWORDS 8
        struct intel_engine_cs *signaller = signaller_req->ring;
        struct drm_device *dev = signaller->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *waiter;
        int i, ret, num_rings;

        num_rings = hweight32(INTEL_INFO(dev)->ring_mask);
        num_dwords += (num_rings-1) * MBOX_UPDATE_DWORDS;
#undef MBOX_UPDATE_DWORDS

        ret = intel_ring_begin(signaller_req, num_dwords);
        if (ret)
                return ret;

        for_each_ring(waiter, dev_priv, i) {
                u32 seqno;
                u64 gtt_offset = signaller->semaphore.signal_ggtt[i];
                if (gtt_offset == MI_SEMAPHORE_SYNC_INVALID)
                        continue;

                seqno = i915_gem_request_get_seqno(signaller_req);
                intel_ring_emit(signaller, GFX_OP_PIPE_CONTROL(6));
                intel_ring_emit(signaller, PIPE_CONTROL_GLOBAL_GTT_IVB |
                                           PIPE_CONTROL_QW_WRITE |
                                           PIPE_CONTROL_FLUSH_ENABLE);
                intel_ring_emit(signaller, lower_32_bits(gtt_offset));
                intel_ring_emit(signaller, upper_32_bits(gtt_offset));
                intel_ring_emit(signaller, seqno);
                intel_ring_emit(signaller, 0);
                intel_ring_emit(signaller, MI_SEMAPHORE_SIGNAL |
                                           MI_SEMAPHORE_TARGET(waiter->id));
                intel_ring_emit(signaller, 0);
        }

        return 0;
}

static int gen8_xcs_signal(struct drm_i915_gem_request *signaller_req,
                           unsigned int num_dwords)
{
#define MBOX_UPDATE_DWORDS 6
        struct intel_engine_cs *signaller = signaller_req->ring;
        struct drm_device *dev = signaller->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *waiter;
        int i, ret, num_rings;

        num_rings = hweight32(INTEL_INFO(dev)->ring_mask);
        num_dwords += (num_rings-1) * MBOX_UPDATE_DWORDS;
#undef MBOX_UPDATE_DWORDS

        ret = intel_ring_begin(signaller_req, num_dwords);
        if (ret)
                return ret;

        for_each_ring(waiter, dev_priv, i) {
                u32 seqno;
                u64 gtt_offset = signaller->semaphore.signal_ggtt[i];
                if (gtt_offset == MI_SEMAPHORE_SYNC_INVALID)
                        continue;

                seqno = i915_gem_request_get_seqno(signaller_req);
                intel_ring_emit(signaller, (MI_FLUSH_DW + 1) |
                                           MI_FLUSH_DW_OP_STOREDW);
                intel_ring_emit(signaller, lower_32_bits(gtt_offset) |
                                           MI_FLUSH_DW_USE_GTT);
                intel_ring_emit(signaller, upper_32_bits(gtt_offset));
                intel_ring_emit(signaller, seqno);
                intel_ring_emit(signaller, MI_SEMAPHORE_SIGNAL |
                                           MI_SEMAPHORE_TARGET(waiter->id));
                intel_ring_emit(signaller, 0);
        }

        return 0;
}

static int gen6_signal(struct drm_i915_gem_request *signaller_req,
                       unsigned int num_dwords)
{
        struct intel_engine_cs *signaller = signaller_req->ring;
        struct drm_device *dev = signaller->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *useless;
        int i, ret, num_rings;

#define MBOX_UPDATE_DWORDS 3
        num_rings = hweight32(INTEL_INFO(dev)->ring_mask);
        num_dwords += round_up((num_rings-1) * MBOX_UPDATE_DWORDS, 2);
#undef MBOX_UPDATE_DWORDS

        ret = intel_ring_begin(signaller_req, num_dwords);
        if (ret)
                return ret;

        for_each_ring(useless, dev_priv, i) {
                u32 mbox_reg = signaller->semaphore.mbox.signal[i];
                if (mbox_reg != GEN6_NOSYNC) {
                        u32 seqno = i915_gem_request_get_seqno(signaller_req);
                        intel_ring_emit(signaller, MI_LOAD_REGISTER_IMM(1));
                        intel_ring_emit(signaller, mbox_reg);
                        intel_ring_emit(signaller, seqno);
                }
        }

        /* If num_dwords was rounded, make sure the tail pointer is correct */
        if (num_rings % 2 == 0)
                intel_ring_emit(signaller, MI_NOOP);

        return 0;
}

/**
 * gen6_add_request - Update the semaphore mailbox registers
 *
 * @request - request to write to the ring
 *
 * Update the mailbox registers in the *other* rings with the current seqno.
 * This acts like a signal in the canonical semaphore.
 */
static int
gen6_add_request(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *ring = req->ring;
        int ret;

        if (ring->semaphore.signal)
                ret = ring->semaphore.signal(req, 4);
        else
                ret = intel_ring_begin(req, 4);

        if (ret)
                return ret;

        intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
        intel_ring_emit(ring, I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
        intel_ring_emit(ring, i915_gem_request_get_seqno(req));
        intel_ring_emit(ring, MI_USER_INTERRUPT);
        __intel_ring_advance(ring);

        return 0;
}

static inline bool i915_gem_has_seqno_wrapped(struct drm_device *dev,
                                              u32 seqno)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        return dev_priv->last_seqno < seqno;
}

/**
 * intel_ring_sync - sync the waiter to the signaller on seqno
 *
 * @waiter - ring that is waiting
 * @signaller - ring which has, or will signal
 * @seqno - seqno which the waiter will block on
 */

static int
gen8_ring_sync(struct drm_i915_gem_request *waiter_req,
               struct intel_engine_cs *signaller,
               u32 seqno)
{
        struct intel_engine_cs *waiter = waiter_req->ring;
        struct drm_i915_private *dev_priv = waiter->dev->dev_private;
        int ret;

        ret = intel_ring_begin(waiter_req, 4);
        if (ret)
                return ret;

        intel_ring_emit(waiter, MI_SEMAPHORE_WAIT |
                                MI_SEMAPHORE_GLOBAL_GTT |
                                MI_SEMAPHORE_POLL |
                                MI_SEMAPHORE_SAD_GTE_SDD);
        intel_ring_emit(waiter, seqno);
        intel_ring_emit(waiter,
                        lower_32_bits(GEN8_WAIT_OFFSET(waiter, signaller->id)));
        intel_ring_emit(waiter,
                        upper_32_bits(GEN8_WAIT_OFFSET(waiter, signaller->id)));
        intel_ring_advance(waiter);
        return 0;
}

static int
gen6_ring_sync(struct drm_i915_gem_request *waiter_req,
               struct intel_engine_cs *signaller,
               u32 seqno)
{
        struct intel_engine_cs *waiter = waiter_req->ring;
        u32 dw1 = MI_SEMAPHORE_MBOX |
                  MI_SEMAPHORE_COMPARE |
                  MI_SEMAPHORE_REGISTER;
        u32 wait_mbox = signaller->semaphore.mbox.wait[waiter->id];
        int ret;

        /* Throughout all of the GEM code, seqno passed implies our current
         * seqno is >= the last seqno executed. However for hardware the
         * comparison is strictly greater than.
         */
        seqno -= 1;

        WARN_ON(wait_mbox == MI_SEMAPHORE_SYNC_INVALID);

        ret = intel_ring_begin(waiter_req, 4);
        if (ret)
                return ret;

        /* If seqno wrap happened, omit the wait with no-ops */
        if (likely(!i915_gem_has_seqno_wrapped(waiter->dev, seqno))) {
                intel_ring_emit(waiter, dw1 | wait_mbox);
                intel_ring_emit(waiter, seqno);
                intel_ring_emit(waiter, 0);
                intel_ring_emit(waiter, MI_NOOP);
        } else {
                intel_ring_emit(waiter, MI_NOOP);
                intel_ring_emit(waiter, MI_NOOP);
                intel_ring_emit(waiter, MI_NOOP);
                intel_ring_emit(waiter, MI_NOOP);
        }
        intel_ring_advance(waiter);

        return 0;
}

#define PIPE_CONTROL_FLUSH(ring__, addr__)                                      \
do {                                                                    \
        intel_ring_emit(ring__, GFX_OP_PIPE_CONTROL(4) | PIPE_CONTROL_QW_WRITE |                \
                 PIPE_CONTROL_DEPTH_STALL);                             \
        intel_ring_emit(ring__, (addr__) | PIPE_CONTROL_GLOBAL_GTT);                    \
        intel_ring_emit(ring__, 0);                                                     \
        intel_ring_emit(ring__, 0);                                                     \
} while (0)

static int
pc_render_add_request(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *ring = req->ring;
        u32 scratch_addr = ring->scratch.gtt_offset + 2 * CACHELINE_BYTES;
        int ret;

        /* For Ironlake, MI_USER_INTERRUPT was deprecated and apparently
         * incoherent with writes to memory, i.e. completely fubar,
         * so we need to use PIPE_NOTIFY instead.
         *
         * However, we also need to workaround the qword write
         * incoherence by flushing the 6 PIPE_NOTIFY buffers out to
         * memory before requesting an interrupt.
         */
        ret = intel_ring_begin(req, 32);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(4) | PIPE_CONTROL_QW_WRITE |
                        PIPE_CONTROL_WRITE_FLUSH |
                        PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE);
        intel_ring_emit(ring, ring->scratch.gtt_offset | PIPE_CONTROL_GLOBAL_GTT);
        intel_ring_emit(ring, i915_gem_request_get_seqno(req));
        intel_ring_emit(ring, 0);
        PIPE_CONTROL_FLUSH(ring, scratch_addr);
        scratch_addr += 2 * CACHELINE_BYTES; /* write to separate cachelines */
        PIPE_CONTROL_FLUSH(ring, scratch_addr);
        scratch_addr += 2 * CACHELINE_BYTES;
        PIPE_CONTROL_FLUSH(ring, scratch_addr);
        scratch_addr += 2 * CACHELINE_BYTES;
        PIPE_CONTROL_FLUSH(ring, scratch_addr);
        scratch_addr += 2 * CACHELINE_BYTES;
        PIPE_CONTROL_FLUSH(ring, scratch_addr);
        scratch_addr += 2 * CACHELINE_BYTES;
        PIPE_CONTROL_FLUSH(ring, scratch_addr);

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(4) | PIPE_CONTROL_QW_WRITE |
                        PIPE_CONTROL_WRITE_FLUSH |
                        PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE |
                        PIPE_CONTROL_NOTIFY);
        intel_ring_emit(ring, ring->scratch.gtt_offset | PIPE_CONTROL_GLOBAL_GTT);
        intel_ring_emit(ring, i915_gem_request_get_seqno(req));
        intel_ring_emit(ring, 0);
        __intel_ring_advance(ring);

        return 0;
}

static u32
gen6_ring_get_seqno(struct intel_engine_cs *ring, bool lazy_coherency)
{
        /* Workaround to force correct ordering between irq and seqno writes on
         * ivb (and maybe also on snb) by reading from a CS register (like
         * ACTHD) before reading the status page. */
        if (!lazy_coherency) {
                struct drm_i915_private *dev_priv = ring->dev->dev_private;
                POSTING_READ(RING_ACTHD(ring->mmio_base));
        }

        return intel_read_status_page(ring, I915_GEM_HWS_INDEX);
}

static u32
ring_get_seqno(struct intel_engine_cs *ring, bool lazy_coherency)
{
        return intel_read_status_page(ring, I915_GEM_HWS_INDEX);
}

static void
ring_set_seqno(struct intel_engine_cs *ring, u32 seqno)
{
        intel_write_status_page(ring, I915_GEM_HWS_INDEX, seqno);
}

static u32
pc_render_get_seqno(struct intel_engine_cs *ring, bool lazy_coherency)
{
        return ring->scratch.cpu_page[0];
}

static void
pc_render_set_seqno(struct intel_engine_cs *ring, u32 seqno)
{
        ring->scratch.cpu_page[0] = seqno;
}

static bool
gen5_ring_get_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        if (WARN_ON(!intel_irqs_enabled(dev_priv)))
                return false;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (ring->irq_refcount++ == 0)
                gen5_enable_gt_irq(dev_priv, ring->irq_enable_mask);
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);

        return true;
}

static void
gen5_ring_put_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (--ring->irq_refcount == 0)
                gen5_disable_gt_irq(dev_priv, ring->irq_enable_mask);
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
}

static bool
i9xx_ring_get_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        if (!intel_irqs_enabled(dev_priv))
                return false;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (ring->irq_refcount++ == 0) {
                dev_priv->irq_mask &= ~ring->irq_enable_mask;
                I915_WRITE(IMR, dev_priv->irq_mask);
                POSTING_READ(IMR);
        }
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);

        return true;
}

static void
i9xx_ring_put_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (--ring->irq_refcount == 0) {
                dev_priv->irq_mask |= ring->irq_enable_mask;
                I915_WRITE(IMR, dev_priv->irq_mask);
                POSTING_READ(IMR);
        }
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
}

static bool
i8xx_ring_get_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        if (!intel_irqs_enabled(dev_priv))
                return false;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (ring->irq_refcount++ == 0) {
                dev_priv->irq_mask &= ~ring->irq_enable_mask;
                I915_WRITE16(IMR, dev_priv->irq_mask);
                POSTING_READ16(IMR);
        }
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);

        return true;
}

static void
i8xx_ring_put_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (--ring->irq_refcount == 0) {
                dev_priv->irq_mask |= ring->irq_enable_mask;
                I915_WRITE16(IMR, dev_priv->irq_mask);
                POSTING_READ16(IMR);
        }
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
}

static int
bsd_ring_flush(struct drm_i915_gem_request *req,
               u32     invalidate_domains,
               u32     flush_domains)
{
        struct intel_engine_cs *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_FLUSH);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);
        return 0;
}

static int
i9xx_add_request(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
        intel_ring_emit(ring, I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
        intel_ring_emit(ring, i915_gem_request_get_seqno(req));
        intel_ring_emit(ring, MI_USER_INTERRUPT);
        __intel_ring_advance(ring);

        return 0;
}

static bool
gen6_ring_get_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        if (WARN_ON(!intel_irqs_enabled(dev_priv)))
                return false;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (ring->irq_refcount++ == 0) {
                if (HAS_L3_DPF(dev) && ring->id == RCS)
                        I915_WRITE_IMR(ring,
                                       ~(ring->irq_enable_mask |
                                         GT_PARITY_ERROR(dev)));
                else
                        I915_WRITE_IMR(ring, ~ring->irq_enable_mask);
                gen5_enable_gt_irq(dev_priv, ring->irq_enable_mask);
        }
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);

        return true;
}

static void
gen6_ring_put_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (--ring->irq_refcount == 0) {
                if (HAS_L3_DPF(dev) && ring->id == RCS)
                        I915_WRITE_IMR(ring, ~GT_PARITY_ERROR(dev));
                else
                        I915_WRITE_IMR(ring, ~0);
                gen5_disable_gt_irq(dev_priv, ring->irq_enable_mask);
        }
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
}

static bool
hsw_vebox_get_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        if (WARN_ON(!intel_irqs_enabled(dev_priv)))
                return false;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (ring->irq_refcount++ == 0) {
                I915_WRITE_IMR(ring, ~ring->irq_enable_mask);
                gen6_enable_pm_irq(dev_priv, ring->irq_enable_mask);
        }
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);

        return true;
}

static void
hsw_vebox_put_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (--ring->irq_refcount == 0) {
                I915_WRITE_IMR(ring, ~0);
                gen6_disable_pm_irq(dev_priv, ring->irq_enable_mask);
        }
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
}

static bool
gen8_ring_get_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        if (WARN_ON(!intel_irqs_enabled(dev_priv)))
                return false;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (ring->irq_refcount++ == 0) {
                if (HAS_L3_DPF(dev) && ring->id == RCS) {
                        I915_WRITE_IMR(ring,
                                       ~(ring->irq_enable_mask |
                                         GT_RENDER_L3_PARITY_ERROR_INTERRUPT));
                } else {
                        I915_WRITE_IMR(ring, ~ring->irq_enable_mask);
                }
                POSTING_READ(RING_IMR(ring->mmio_base));
        }
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);

        return true;
}

static void
gen8_ring_put_irq(struct intel_engine_cs *ring)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;

        spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (--ring->irq_refcount == 0) {
                if (HAS_L3_DPF(dev) && ring->id == RCS) {
                        I915_WRITE_IMR(ring,
                                       ~GT_RENDER_L3_PARITY_ERROR_INTERRUPT);
                } else {
                        I915_WRITE_IMR(ring, ~0);
                }
                POSTING_READ(RING_IMR(ring->mmio_base));
        }
        spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
}

static int
i965_dispatch_execbuffer(struct drm_i915_gem_request *req,
                         u64 offset, u32 length,
                         unsigned dispatch_flags)
{
        struct intel_engine_cs *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring,
                        MI_BATCH_BUFFER_START |
                        MI_BATCH_GTT |
                        (dispatch_flags & I915_DISPATCH_SECURE ?
                         0 : MI_BATCH_NON_SECURE_I965));
        intel_ring_emit(ring, offset);
        intel_ring_advance(ring);

        return 0;
}

/* Just userspace ABI convention to limit the wa batch bo to a resonable size */
#define I830_BATCH_LIMIT (256*1024)
#define I830_TLB_ENTRIES (2)
#define I830_WA_SIZE max(I830_TLB_ENTRIES*4096, I830_BATCH_LIMIT)
static int
i830_dispatch_execbuffer(struct drm_i915_gem_request *req,
                         u64 offset, u32 len,
                         unsigned dispatch_flags)
{
        struct intel_engine_cs *ring = req->ring;
        u32 cs_offset = ring->scratch.gtt_offset;
        int ret;

        ret = intel_ring_begin(req, 6);
        if (ret)
                return ret;

        /* Evict the invalid PTE TLBs */
        intel_ring_emit(ring, COLOR_BLT_CMD | BLT_WRITE_RGBA);
        intel_ring_emit(ring, BLT_DEPTH_32 | BLT_ROP_COLOR_COPY | 4096);
        intel_ring_emit(ring, I830_TLB_ENTRIES << 16 | 4); /* load each page */
        intel_ring_emit(ring, cs_offset);
        intel_ring_emit(ring, 0xdeadbeef);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        if ((dispatch_flags & I915_DISPATCH_PINNED) == 0) {
                if (len > I830_BATCH_LIMIT)
                        return -ENOSPC;

                ret = intel_ring_begin(req, 6 + 2);
                if (ret)
                        return ret;

                /* Blit the batch (which has now all relocs applied) to the
                 * stable batch scratch bo area (so that the CS never
                 * stumbles over its tlb invalidation bug) ...
                 */
                intel_ring_emit(ring, SRC_COPY_BLT_CMD | BLT_WRITE_RGBA);
                intel_ring_emit(ring, BLT_DEPTH_32 | BLT_ROP_SRC_COPY | 4096);
                intel_ring_emit(ring, DIV_ROUND_UP(len, 4096) << 16 | 4096);
                intel_ring_emit(ring, cs_offset);
                intel_ring_emit(ring, 4096);
                intel_ring_emit(ring, offset);

                intel_ring_emit(ring, MI_FLUSH);
                intel_ring_emit(ring, MI_NOOP);
                intel_ring_advance(ring);

                /* ... and execute it. */
                offset = cs_offset;
        }

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_BATCH_BUFFER);
        intel_ring_emit(ring, offset | (dispatch_flags & I915_DISPATCH_SECURE ?
                                        0 : MI_BATCH_NON_SECURE));
        intel_ring_emit(ring, offset + len - 8);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

static int
i915_dispatch_execbuffer(struct drm_i915_gem_request *req,
                         u64 offset, u32 len,
                         unsigned dispatch_flags)
{
        struct intel_engine_cs *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_BATCH_BUFFER_START | MI_BATCH_GTT);
        intel_ring_emit(ring, offset | (dispatch_flags & I915_DISPATCH_SECURE ?
                                        0 : MI_BATCH_NON_SECURE));
        intel_ring_advance(ring);

        return 0;
}

static void cleanup_status_page(struct intel_engine_cs *ring)
{
        struct drm_i915_gem_object *obj;

        obj = ring->status_page.obj;
        if (obj == NULL)
                return;

        kunmap(sg_page(obj->pages->sgl));
        i915_gem_object_ggtt_unpin(obj);
        drm_gem_object_unreference(&obj->base);
        ring->status_page.obj = NULL;
}

static int init_status_page(struct intel_engine_cs *ring)
{
        struct drm_i915_gem_object *obj;

        if ((obj = ring->status_page.obj) == NULL) {
                unsigned flags;
                int ret;

                obj = i915_gem_alloc_object(ring->dev, 4096);
                if (obj == NULL) {
                        DRM_ERROR("Failed to allocate status page\n");
                        return -ENOMEM;
                }

                ret = i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
                if (ret)
                        goto err_unref;

                flags = 0;
                if (!HAS_LLC(ring->dev))
                        /* On g33, we cannot place HWS above 256MiB, so
                         * restrict its pinning to the low mappable arena.
                         * Though this restriction is not documented for
                         * gen4, gen5, or byt, they also behave similarly
                         * and hang if the HWS is placed at the top of the
                         * GTT. To generalise, it appears that all !llc
                         * platforms have issues with us placing the HWS
                         * above the mappable region (even though we never
                         * actualy map it).
                         */
                        flags |= PIN_MAPPABLE;
                ret = i915_gem_obj_ggtt_pin(obj, 4096, flags);
                if (ret) {
err_unref:
                        drm_gem_object_unreference(&obj->base);
                        return ret;
                }

                ring->status_page.obj = obj;
        }

        ring->status_page.gfx_addr = i915_gem_obj_ggtt_offset(obj);
        ring->status_page.page_addr = kmap(sg_page(obj->pages->sgl));
        memset(ring->status_page.page_addr, 0, PAGE_SIZE);

        DRM_DEBUG_DRIVER("%s hws offset: 0x%08x\n",
                        ring->name, ring->status_page.gfx_addr);

        return 0;
}

static int init_phys_status_page(struct intel_engine_cs *ring)
{
        struct drm_i915_private *dev_priv = ring->dev->dev_private;

        if (!dev_priv->status_page_dmah) {
                dev_priv->status_page_dmah =
                        drm_pci_alloc(ring->dev, PAGE_SIZE, PAGE_SIZE);
                if (!dev_priv->status_page_dmah)
                        return -ENOMEM;
        }

        ring->status_page.page_addr = dev_priv->status_page_dmah->vaddr;
        memset(ring->status_page.page_addr, 0, PAGE_SIZE);

        return 0;
}

void intel_unpin_ringbuffer_obj(struct intel_ringbuffer *ringbuf)
{
        if (HAS_LLC(ringbuf->obj->base.dev) && !ringbuf->obj->stolen)
                vunmap(ringbuf->virtual_start);
        else
                iounmap(ringbuf->virtual_start);
        ringbuf->virtual_start = NULL;
        i915_gem_object_ggtt_unpin(ringbuf->obj);
}

static u32 *vmap_obj(struct drm_i915_gem_object *obj)
{
        struct sg_page_iter sg_iter;
        struct page **pages;
        void *addr;
        int i;

        pages = drm_malloc_ab(obj->base.size >> PAGE_SHIFT, sizeof(*pages));
        if (pages == NULL)
                return NULL;

        i = 0;
        for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0)
                pages[i++] = sg_page_iter_page(&sg_iter);

        addr = vmap(pages, i, 0, PAGE_KERNEL);
        drm_free_large(pages);

        return addr;
}

int intel_pin_and_map_ringbuffer_obj(struct drm_device *dev,
                                     struct intel_ringbuffer *ringbuf)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct drm_i915_gem_object *obj = ringbuf->obj;
        int ret;

        if (HAS_LLC(dev_priv) && !obj->stolen) {
                ret = i915_gem_obj_ggtt_pin(obj, PAGE_SIZE, 0);
                if (ret)
                        return ret;

                ret = i915_gem_object_set_to_cpu_domain(obj, true);
                if (ret) {
                        i915_gem_object_ggtt_unpin(obj);
                        return ret;
                }

                ringbuf->virtual_start = vmap_obj(obj);
                if (ringbuf->virtual_start == NULL) {
                        i915_gem_object_ggtt_unpin(obj);
                        return -ENOMEM;
                }
        } else {
                ret = i915_gem_obj_ggtt_pin(obj, PAGE_SIZE, PIN_MAPPABLE);
                if (ret)
                        return ret;

                ret = i915_gem_object_set_to_gtt_domain(obj, true);
                if (ret) {
                        i915_gem_object_ggtt_unpin(obj);
                        return ret;
                }

                ringbuf->virtual_start = ioremap_wc(dev_priv->gtt.mappable_base +
                                                    i915_gem_obj_ggtt_offset(obj), ringbuf->size);
                if (ringbuf->virtual_start == NULL) {
                        i915_gem_object_ggtt_unpin(obj);
                        return -EINVAL;
                }
        }

        return 0;
}

static void intel_destroy_ringbuffer_obj(struct intel_ringbuffer *ringbuf)
{
        drm_gem_object_unreference(&ringbuf->obj->base);
        ringbuf->obj = NULL;
}

static int intel_alloc_ringbuffer_obj(struct drm_device *dev,
                                      struct intel_ringbuffer *ringbuf)
{
        struct drm_i915_gem_object *obj;

        obj = NULL;
        if (!HAS_LLC(dev))
                obj = i915_gem_object_create_stolen(dev, ringbuf->size);
        if (obj == NULL)
                obj = i915_gem_alloc_object(dev, ringbuf->size);
        if (obj == NULL)
                return -ENOMEM;

        /* mark ring buffers as read-only from GPU side by default */
        obj->gt_ro = 1;

        ringbuf->obj = obj;

        return 0;
}

struct intel_ringbuffer *
intel_engine_create_ringbuffer(struct intel_engine_cs *engine, int size)
{
        struct intel_ringbuffer *ring;
        int ret;

        ring = kzalloc(sizeof(*ring), GFP_KERNEL);
        if (ring == NULL)
                return ERR_PTR(-ENOMEM);

        ring->ring = engine;

        ring->size = size;
        /* Workaround an erratum on the i830 which causes a hang if
         * the TAIL pointer points to within the last 2 cachelines
         * of the buffer.
         */
        ring->effective_size = size;
        if (IS_I830(engine->dev) || IS_845G(engine->dev))
                ring->effective_size -= 2 * CACHELINE_BYTES;

        ring->last_retired_head = -1;
        intel_ring_update_space(ring);

        ret = intel_alloc_ringbuffer_obj(engine->dev, ring);
        if (ret) {
                DRM_ERROR("Failed to allocate ringbuffer %s: %d\n",
                          engine->name, ret);
                kfree(ring);
                return ERR_PTR(ret);
        }

        return ring;
}

void
intel_ringbuffer_free(struct intel_ringbuffer *ring)
{
        intel_destroy_ringbuffer_obj(ring);
        kfree(ring);
}

static int intel_init_ring_buffer(struct drm_device *dev,
                                  struct intel_engine_cs *ring)
{
        struct intel_ringbuffer *ringbuf;
        int ret;

        WARN_ON(ring->buffer);

        ring->dev = dev;
        INIT_LIST_HEAD(&ring->active_list);
        INIT_LIST_HEAD(&ring->request_list);
        INIT_LIST_HEAD(&ring->execlist_queue);
        i915_gem_batch_pool_init(dev, &ring->batch_pool);
        memset(ring->semaphore.sync_seqno, 0, sizeof(ring->semaphore.sync_seqno));

        init_waitqueue_head(&ring->irq_queue);

        ringbuf = intel_engine_create_ringbuffer(ring, 32 * PAGE_SIZE);
        if (IS_ERR(ringbuf))
                return PTR_ERR(ringbuf);
        ring->buffer = ringbuf;

        if (I915_NEED_GFX_HWS(dev)) {
                ret = init_status_page(ring);
                if (ret)
                        goto error;
        } else {
                BUG_ON(ring->id != RCS);
                ret = init_phys_status_page(ring);
                if (ret)
                        goto error;
        }

        ret = intel_pin_and_map_ringbuffer_obj(dev, ringbuf);
        if (ret) {
                DRM_ERROR("Failed to pin and map ringbuffer %s: %d\n",
                                ring->name, ret);
                intel_destroy_ringbuffer_obj(ringbuf);
                goto error;
        }

        ret = i915_cmd_parser_init_ring(ring);
        if (ret)
                goto error;

        return 0;

error:
        intel_ringbuffer_free(ringbuf);
        ring->buffer = NULL;
        return ret;
}

void intel_cleanup_ring_buffer(struct intel_engine_cs *ring)
{
        struct drm_i915_private *dev_priv;

        if (!intel_ring_initialized(ring))
                return;

        dev_priv = to_i915(ring->dev);

        intel_stop_ring_buffer(ring);
        WARN_ON(!IS_GEN2(ring->dev) && (I915_READ_MODE(ring) & MODE_IDLE) == 0);

        intel_unpin_ringbuffer_obj(ring->buffer);
        intel_ringbuffer_free(ring->buffer);
        ring->buffer = NULL;

        if (ring->cleanup)
                ring->cleanup(ring);

        cleanup_status_page(ring);

        i915_cmd_parser_fini_ring(ring);
        i915_gem_batch_pool_fini(&ring->batch_pool);
}

static int ring_wait_for_space(struct intel_engine_cs *ring, int n)
{
        struct intel_ringbuffer *ringbuf = ring->buffer;
        struct drm_i915_gem_request *request;
        unsigned space;
        int ret;

        if (intel_ring_space(ringbuf) >= n)
                return 0;

        /* The whole point of reserving space is to not wait! */
        WARN_ON(ringbuf->reserved_in_use);

        list_for_each_entry(request, &ring->request_list, list) {
                space = __intel_ring_space(request->postfix, ringbuf->tail,
                                           ringbuf->size);
                if (space >= n)
                        break;
        }

        if (WARN_ON(&request->list == &ring->request_list))
                return -ENOSPC;

        ret = i915_wait_request(request);
        if (ret)
                return ret;

        ringbuf->space = space;
        return 0;
}

static void __wrap_ring_buffer(struct intel_ringbuffer *ringbuf)
{
        uint32_t __iomem *virt;
        int rem = ringbuf->size - ringbuf->tail;

        virt = ringbuf->virtual_start + ringbuf->tail;
        rem /= 4;
        while (rem--)
                iowrite32(MI_NOOP, virt++);

        ringbuf->tail = 0;
        intel_ring_update_space(ringbuf);
}

int intel_ring_idle(struct intel_engine_cs *ring)
{
        struct drm_i915_gem_request *req;

        /* Wait upon the last request to be completed */
        if (list_empty(&ring->request_list))
                return 0;

        req = list_entry(ring->request_list.prev,
                        struct drm_i915_gem_request,
                        list);

        /* Make sure we do not trigger any retires */
        return __i915_wait_request(req,
                                   atomic_read(&to_i915(ring->dev)->gpu_error.reset_counter),
                                   to_i915(ring->dev)->mm.interruptible,
                                   NULL, NULL);
}

int intel_ring_alloc_request_extras(struct drm_i915_gem_request *request)
{
        request->ringbuf = request->ring->buffer;
        return 0;
}

int intel_ring_reserve_space(struct drm_i915_gem_request *request)
{
        /*
         * The first call merely notes the reserve request and is common for
         * all back ends. The subsequent localised _begin() call actually
         * ensures that the reservation is available. Without the begin, if
         * the request creator immediately submitted the request without
         * adding any commands to it then there might not actually be
         * sufficient room for the submission commands.
         */
        intel_ring_reserved_space_reserve(request->ringbuf, MIN_SPACE_FOR_ADD_REQUEST);

        return intel_ring_begin(request, 0);
}

void intel_ring_reserved_space_reserve(struct intel_ringbuffer *ringbuf, int size)
{
        WARN_ON(ringbuf->reserved_size);
        WARN_ON(ringbuf->reserved_in_use);

        ringbuf->reserved_size = size;
}

void intel_ring_reserved_space_cancel(struct intel_ringbuffer *ringbuf)
{
        WARN_ON(ringbuf->reserved_in_use);

        ringbuf->reserved_size   = 0;
        ringbuf->reserved_in_use = false;
}

void intel_ring_reserved_space_use(struct intel_ringbuffer *ringbuf)
{
        WARN_ON(ringbuf->reserved_in_use);

        ringbuf->reserved_in_use = true;
        ringbuf->reserved_tail   = ringbuf->tail;
}

void intel_ring_reserved_space_end(struct intel_ringbuffer *ringbuf)
{
        WARN_ON(!ringbuf->reserved_in_use);
        if (ringbuf->tail > ringbuf->reserved_tail) {
                WARN(ringbuf->tail > ringbuf->reserved_tail + ringbuf->reserved_size,
                     "request reserved size too small: %d vs %d!\n",
                     ringbuf->tail - ringbuf->reserved_tail, ringbuf->reserved_size);
        } else {
                /*
                 * The ring was wrapped while the reserved space was in use.
                 * That means that some unknown amount of the ring tail was
                 * no-op filled and skipped. Thus simply adding the ring size
                 * to the tail and doing the above space check will not work.
                 * Rather than attempt to track how much tail was skipped,
                 * it is much simpler to say that also skipping the sanity
                 * check every once in a while is not a big issue.
                 */
        }

        ringbuf->reserved_size   = 0;
        ringbuf->reserved_in_use = false;
}

static int __intel_ring_prepare(struct intel_engine_cs *ring, int bytes)
{
        struct intel_ringbuffer *ringbuf = ring->buffer;
        int remain_usable = ringbuf->effective_size - ringbuf->tail;
        int remain_actual = ringbuf->size - ringbuf->tail;
        int ret, total_bytes, wait_bytes = 0;
        bool need_wrap = false;

        if (ringbuf->reserved_in_use)
                total_bytes = bytes;
        else
                total_bytes = bytes + ringbuf->reserved_size;

        if (unlikely(bytes > remain_usable)) {
                /*
                 * Not enough space for the basic request. So need to flush
                 * out the remainder and then wait for base + reserved.
                 */
                wait_bytes = remain_actual + total_bytes;
                need_wrap = true;
        } else {
                if (unlikely(total_bytes > remain_usable)) {
                        /*
                         * The base request will fit but the reserved space
                         * falls off the end. So only need to to wait for the
                         * reserved size after flushing out the remainder.
                         */
                        wait_bytes = remain_actual + ringbuf->reserved_size;
                        need_wrap = true;
                } else if (total_bytes > ringbuf->space) {
                        /* No wrapping required, just waiting. */
                        wait_bytes = total_bytes;
                }
        }

        if (wait_bytes) {
                ret = ring_wait_for_space(ring, wait_bytes);
                if (unlikely(ret))
                        return ret;

                if (need_wrap)
                        __wrap_ring_buffer(ringbuf);
        }

        return 0;
}

int intel_ring_begin(struct drm_i915_gem_request *req,
                     int num_dwords)
{
        struct intel_engine_cs *ring;
        struct drm_i915_private *dev_priv;
        int ret;

        WARN_ON(req == NULL);
        ring = req->ring;
        dev_priv = ring->dev->dev_private;

        ret = i915_gem_check_wedge(&dev_priv->gpu_error,
                                   dev_priv->mm.interruptible);
        if (ret)
                return ret;

        ret = __intel_ring_prepare(ring, num_dwords * sizeof(uint32_t));
        if (ret)
                return ret;

        ring->buffer->space -= num_dwords * sizeof(uint32_t);
        return 0;
}

/* Align the ring tail to a cacheline boundary */
int intel_ring_cacheline_align(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *ring = req->ring;
        int num_dwords = (ring->buffer->tail & (CACHELINE_BYTES - 1)) / sizeof(uint32_t);
        int ret;

        if (num_dwords == 0)
                return 0;

        num_dwords = CACHELINE_BYTES / sizeof(uint32_t) - num_dwords;
        ret = intel_ring_begin(req, num_dwords);
        if (ret)
                return ret;

        while (num_dwords--)
                intel_ring_emit(ring, MI_NOOP);

        intel_ring_advance(ring);

        return 0;
}

void intel_ring_init_seqno(struct intel_engine_cs *ring, u32 seqno)
{
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        if (INTEL_INFO(dev)->gen == 6 || INTEL_INFO(dev)->gen == 7) {
                I915_WRITE(RING_SYNC_0(ring->mmio_base), 0);
                I915_WRITE(RING_SYNC_1(ring->mmio_base), 0);
                if (HAS_VEBOX(dev))
                        I915_WRITE(RING_SYNC_2(ring->mmio_base), 0);
        }

        ring->set_seqno(ring, seqno);
        ring->hangcheck.seqno = seqno;
}

static void gen6_bsd_ring_write_tail(struct intel_engine_cs *ring,
                                     u32 value)
{
        struct drm_i915_private *dev_priv = ring->dev->dev_private;

       /* Every tail move must follow the sequence below */

        /* Disable notification that the ring is IDLE. The GT
         * will then assume that it is busy and bring it out of rc6.
         */
        I915_WRITE(GEN6_BSD_SLEEP_PSMI_CONTROL,
                   _MASKED_BIT_ENABLE(GEN6_BSD_SLEEP_MSG_DISABLE));

        /* Clear the context id. Here be magic! */
        I915_WRITE64(GEN6_BSD_RNCID, 0x0);

        /* Wait for the ring not to be idle, i.e. for it to wake up. */
        if (wait_for((I915_READ(GEN6_BSD_SLEEP_PSMI_CONTROL) &
                      GEN6_BSD_SLEEP_INDICATOR) == 0,
                     50))
                DRM_ERROR("timed out waiting for the BSD ring to wake up\n");

        /* Now that the ring is fully powered up, update the tail */
        I915_WRITE_TAIL(ring, value);
        POSTING_READ(RING_TAIL(ring->mmio_base));

        /* Let the ring send IDLE messages to the GT again,
         * and so let it sleep to conserve power when idle.
         */
        I915_WRITE(GEN6_BSD_SLEEP_PSMI_CONTROL,
                   _MASKED_BIT_DISABLE(GEN6_BSD_SLEEP_MSG_DISABLE));
}

static int gen6_bsd_ring_flush(struct drm_i915_gem_request *req,
                               u32 invalidate, u32 flush)
{
        struct intel_engine_cs *ring = req->ring;
        uint32_t cmd;
        int ret;

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        cmd = MI_FLUSH_DW;
        if (INTEL_INFO(ring->dev)->gen >= 8)
                cmd += 1;

        /* We always require a command barrier so that subsequent
         * commands, such as breadcrumb interrupts, are strictly ordered
         * wrt the contents of the write cache being flushed to memory
         * (and thus being coherent from the CPU).
         */
        cmd |= MI_FLUSH_DW_STORE_INDEX | MI_FLUSH_DW_OP_STOREDW;

        /*
         * Bspec vol 1c.5 - video engine command streamer:
         * "If ENABLED, all TLBs will be invalidated once the flush
         * operation is complete. This bit is only valid when the
         * Post-Sync Operation field is a value of 1h or 3h."
         */
        if (invalidate & I915_GEM_GPU_DOMAINS)
                cmd |= MI_INVALIDATE_TLB | MI_INVALIDATE_BSD;

        intel_ring_emit(ring, cmd);
        intel_ring_emit(ring, I915_GEM_HWS_SCRATCH_ADDR | MI_FLUSH_DW_USE_GTT);
        if (INTEL_INFO(ring->dev)->gen >= 8) {
                intel_ring_emit(ring, 0); /* upper addr */
                intel_ring_emit(ring, 0); /* value */
        } else  {
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, MI_NOOP);
        }
        intel_ring_advance(ring);
        return 0;
}

static int
gen8_ring_dispatch_execbuffer(struct drm_i915_gem_request *req,
                              u64 offset, u32 len,
                              unsigned dispatch_flags)
{
        struct intel_engine_cs *ring = req->ring;
        bool ppgtt = USES_PPGTT(ring->dev) &&
                        !(dispatch_flags & I915_DISPATCH_SECURE);
        int ret;

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        /* FIXME(BDW): Address space and security selectors. */
        intel_ring_emit(ring, MI_BATCH_BUFFER_START_GEN8 | (ppgtt<<8) |
                        (dispatch_flags & I915_DISPATCH_RS ?
                         MI_BATCH_RESOURCE_STREAMER : 0));
        intel_ring_emit(ring, lower_32_bits(offset));
        intel_ring_emit(ring, upper_32_bits(offset));
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

static int
hsw_ring_dispatch_execbuffer(struct drm_i915_gem_request *req,
                             u64 offset, u32 len,
                             unsigned dispatch_flags)
{
        struct intel_engine_cs *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring,
                        MI_BATCH_BUFFER_START |
                        (dispatch_flags & I915_DISPATCH_SECURE ?
                         0 : MI_BATCH_PPGTT_HSW | MI_BATCH_NON_SECURE_HSW) |
                        (dispatch_flags & I915_DISPATCH_RS ?
                         MI_BATCH_RESOURCE_STREAMER : 0));
        /* bit0-7 is the length on GEN6+ */
        intel_ring_emit(ring, offset);
        intel_ring_advance(ring);

        return 0;
}

static int
gen6_ring_dispatch_execbuffer(struct drm_i915_gem_request *req,
                              u64 offset, u32 len,
                              unsigned dispatch_flags)
{
        struct intel_engine_cs *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring,
                        MI_BATCH_BUFFER_START |
                        (dispatch_flags & I915_DISPATCH_SECURE ?
                         0 : MI_BATCH_NON_SECURE_I965));
        /* bit0-7 is the length on GEN6+ */
        intel_ring_emit(ring, offset);
        intel_ring_advance(ring);

        return 0;
}

/* Blitter support (SandyBridge+) */

static int gen6_ring_flush(struct drm_i915_gem_request *req,
                           u32 invalidate, u32 flush)
{
        struct intel_engine_cs *ring = req->ring;
        struct drm_device *dev = ring->dev;
        uint32_t cmd;
        int ret;

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        cmd = MI_FLUSH_DW;
        if (INTEL_INFO(dev)->gen >= 8)
                cmd += 1;

        /* We always require a command barrier so that subsequent
         * commands, such as breadcrumb interrupts, are strictly ordered
         * wrt the contents of the write cache being flushed to memory
         * (and thus being coherent from the CPU).
         */
        cmd |= MI_FLUSH_DW_STORE_INDEX | MI_FLUSH_DW_OP_STOREDW;

        /*
         * Bspec vol 1c.3 - blitter engine command streamer:
         * "If ENABLED, all TLBs will be invalidated once the flush
         * operation is complete. This bit is only valid when the
         * Post-Sync Operation field is a value of 1h or 3h."
         */
        if (invalidate & I915_GEM_DOMAIN_RENDER)
                cmd |= MI_INVALIDATE_TLB;
        intel_ring_emit(ring, cmd);
        intel_ring_emit(ring, I915_GEM_HWS_SCRATCH_ADDR | MI_FLUSH_DW_USE_GTT);
        if (INTEL_INFO(dev)->gen >= 8) {
                intel_ring_emit(ring, 0); /* upper addr */
                intel_ring_emit(ring, 0); /* value */
        } else  {
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, MI_NOOP);
        }
        intel_ring_advance(ring);

        return 0;
}

int intel_init_render_ring_buffer(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring = &dev_priv->ring[RCS];
        struct drm_i915_gem_object *obj;
        int ret;

        ring->name = "render ring";
        ring->id = RCS;
        ring->mmio_base = RENDER_RING_BASE;

        if (INTEL_INFO(dev)->gen >= 8) {
                if (i915_semaphore_is_enabled(dev)) {
                        obj = i915_gem_alloc_object(dev, 4096);
                        if (obj == NULL) {
                                DRM_ERROR("Failed to allocate semaphore bo. Disabling semaphores\n");
                                i915.semaphores = 0;
                        } else {
                                i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
                                ret = i915_gem_obj_ggtt_pin(obj, 0, PIN_NONBLOCK);
                                if (ret != 0) {
                                        drm_gem_object_unreference(&obj->base);
                                        DRM_ERROR("Failed to pin semaphore bo. Disabling semaphores\n");
                                        i915.semaphores = 0;
                                } else
                                        dev_priv->semaphore_obj = obj;
                        }
                }

                ring->init_context = intel_rcs_ctx_init;
                ring->add_request = gen6_add_request;
                ring->flush = gen8_render_ring_flush;
                ring->irq_get = gen8_ring_get_irq;
                ring->irq_put = gen8_ring_put_irq;
                ring->irq_enable_mask = GT_RENDER_USER_INTERRUPT;
                ring->get_seqno = gen6_ring_get_seqno;
                ring->set_seqno = ring_set_seqno;
                if (i915_semaphore_is_enabled(dev)) {
                        WARN_ON(!dev_priv->semaphore_obj);
                        ring->semaphore.sync_to = gen8_ring_sync;
                        ring->semaphore.signal = gen8_rcs_signal;
                        GEN8_RING_SEMAPHORE_INIT;
                }
        } else if (INTEL_INFO(dev)->gen >= 6) {
                ring->init_context = intel_rcs_ctx_init;
                ring->add_request = gen6_add_request;
                ring->flush = gen7_render_ring_flush;
                if (INTEL_INFO(dev)->gen == 6)
                        ring->flush = gen6_render_ring_flush;
                ring->irq_get = gen6_ring_get_irq;
                ring->irq_put = gen6_ring_put_irq;
                ring->irq_enable_mask = GT_RENDER_USER_INTERRUPT;
                ring->get_seqno = gen6_ring_get_seqno;
                ring->set_seqno = ring_set_seqno;
                if (i915_semaphore_is_enabled(dev)) {
                        ring->semaphore.sync_to = gen6_ring_sync;
                        ring->semaphore.signal = gen6_signal;
                        /*
                         * The current semaphore is only applied on pre-gen8
                         * platform.  And there is no VCS2 ring on the pre-gen8
                         * platform. So the semaphore between RCS and VCS2 is
                         * initialized as INVALID.  Gen8 will initialize the
                         * sema between VCS2 and RCS later.
                         */
                        ring->semaphore.mbox.wait[RCS] = MI_SEMAPHORE_SYNC_INVALID;
                        ring->semaphore.mbox.wait[VCS] = MI_SEMAPHORE_SYNC_RV;
                        ring->semaphore.mbox.wait[BCS] = MI_SEMAPHORE_SYNC_RB;
                        ring->semaphore.mbox.wait[VECS] = MI_SEMAPHORE_SYNC_RVE;
                        ring->semaphore.mbox.wait[VCS2] = MI_SEMAPHORE_SYNC_INVALID;
                        ring->semaphore.mbox.signal[RCS] = GEN6_NOSYNC;
                        ring->semaphore.mbox.signal[VCS] = GEN6_VRSYNC;
                        ring->semaphore.mbox.signal[BCS] = GEN6_BRSYNC;
                        ring->semaphore.mbox.signal[VECS] = GEN6_VERSYNC;
                        ring->semaphore.mbox.signal[VCS2] = GEN6_NOSYNC;
                }
        } else if (IS_GEN5(dev)) {
                ring->add_request = pc_render_add_request;
                ring->flush = gen4_render_ring_flush;
                ring->get_seqno = pc_render_get_seqno;
                ring->set_seqno = pc_render_set_seqno;
                ring->irq_get = gen5_ring_get_irq;
                ring->irq_put = gen5_ring_put_irq;
                ring->irq_enable_mask = GT_RENDER_USER_INTERRUPT |
                                        GT_RENDER_PIPECTL_NOTIFY_INTERRUPT;
        } else {
                ring->add_request = i9xx_add_request;
                if (INTEL_INFO(dev)->gen < 4)
                        ring->flush = gen2_render_ring_flush;
                else
                        ring->flush = gen4_render_ring_flush;
                ring->get_seqno = ring_get_seqno;
                ring->set_seqno = ring_set_seqno;
                if (IS_GEN2(dev)) {
                        ring->irq_get = i8xx_ring_get_irq;
                        ring->irq_put = i8xx_ring_put_irq;
                } else {
                        ring->irq_get = i9xx_ring_get_irq;
                        ring->irq_put = i9xx_ring_put_irq;
                }
                ring->irq_enable_mask = I915_USER_INTERRUPT;
        }
        ring->write_tail = ring_write_tail;

        if (IS_HASWELL(dev))
                ring->dispatch_execbuffer = hsw_ring_dispatch_execbuffer;
        else if (IS_GEN8(dev))
                ring->dispatch_execbuffer = gen8_ring_dispatch_execbuffer;
        else if (INTEL_INFO(dev)->gen >= 6)
                ring->dispatch_execbuffer = gen6_ring_dispatch_execbuffer;
        else if (INTEL_INFO(dev)->gen >= 4)
                ring->dispatch_execbuffer = i965_dispatch_execbuffer;
        else if (IS_I830(dev) || IS_845G(dev))
                ring->dispatch_execbuffer = i830_dispatch_execbuffer;
        else
                ring->dispatch_execbuffer = i915_dispatch_execbuffer;
        ring->init_hw = init_render_ring;
        ring->cleanup = render_ring_cleanup;

        /* Workaround batchbuffer to combat CS tlb bug. */
        if (HAS_BROKEN_CS_TLB(dev)) {
                obj = i915_gem_alloc_object(dev, I830_WA_SIZE);
                if (obj == NULL) {
                        DRM_ERROR("Failed to allocate batch bo\n");
                        return -ENOMEM;
                }

                ret = i915_gem_obj_ggtt_pin(obj, 0, 0);
                if (ret != 0) {
                        drm_gem_object_unreference(&obj->base);
                        DRM_ERROR("Failed to ping batch bo\n");
                        return ret;
                }

                ring->scratch.obj = obj;
                ring->scratch.gtt_offset = i915_gem_obj_ggtt_offset(obj);
        }

        ret = intel_init_ring_buffer(dev, ring);
        if (ret)
                return ret;

        if (INTEL_INFO(dev)->gen >= 5) {
                ret = intel_init_pipe_control(ring);
                if (ret)
                        return ret;
        }

        return 0;
}

int intel_init_bsd_ring_buffer(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring = &dev_priv->ring[VCS];

        ring->name = "bsd ring";
        ring->id = VCS;

        ring->write_tail = ring_write_tail;
        if (INTEL_INFO(dev)->gen >= 6) {
                ring->mmio_base = GEN6_BSD_RING_BASE;
                /* gen6 bsd needs a special wa for tail updates */
                if (IS_GEN6(dev))
                        ring->write_tail = gen6_bsd_ring_write_tail;
                ring->flush = gen6_bsd_ring_flush;
                ring->add_request = gen6_add_request;
                ring->get_seqno = gen6_ring_get_seqno;
                ring->set_seqno = ring_set_seqno;
                if (INTEL_INFO(dev)->gen >= 8) {
                        ring->irq_enable_mask =
                                GT_RENDER_USER_INTERRUPT << GEN8_VCS1_IRQ_SHIFT;
                        ring->irq_get = gen8_ring_get_irq;
                        ring->irq_put = gen8_ring_put_irq;
                        ring->dispatch_execbuffer =
                                gen8_ring_dispatch_execbuffer;
                        if (i915_semaphore_is_enabled(dev)) {
                                ring->semaphore.sync_to = gen8_ring_sync;
                                ring->semaphore.signal = gen8_xcs_signal;
                                GEN8_RING_SEMAPHORE_INIT;
                        }
                } else {
                        ring->irq_enable_mask = GT_BSD_USER_INTERRUPT;
                        ring->irq_get = gen6_ring_get_irq;
                        ring->irq_put = gen6_ring_put_irq;
                        ring->dispatch_execbuffer =
                                gen6_ring_dispatch_execbuffer;
                        if (i915_semaphore_is_enabled(dev)) {
                                ring->semaphore.sync_to = gen6_ring_sync;
                                ring->semaphore.signal = gen6_signal;
                                ring->semaphore.mbox.wait[RCS] = MI_SEMAPHORE_SYNC_VR;
                                ring->semaphore.mbox.wait[VCS] = MI_SEMAPHORE_SYNC_INVALID;
                                ring->semaphore.mbox.wait[BCS] = MI_SEMAPHORE_SYNC_VB;
                                ring->semaphore.mbox.wait[VECS] = MI_SEMAPHORE_SYNC_VVE;
                                ring->semaphore.mbox.wait[VCS2] = MI_SEMAPHORE_SYNC_INVALID;
                                ring->semaphore.mbox.signal[RCS] = GEN6_RVSYNC;
                                ring->semaphore.mbox.signal[VCS] = GEN6_NOSYNC;
                                ring->semaphore.mbox.signal[BCS] = GEN6_BVSYNC;
                                ring->semaphore.mbox.signal[VECS] = GEN6_VEVSYNC;
                                ring->semaphore.mbox.signal[VCS2] = GEN6_NOSYNC;
                        }
                }
        } else {
                ring->mmio_base = BSD_RING_BASE;
                ring->flush = bsd_ring_flush;
                ring->add_request = i9xx_add_request;
                ring->get_seqno = ring_get_seqno;
                ring->set_seqno = ring_set_seqno;
                if (IS_GEN5(dev)) {
                        ring->irq_enable_mask = ILK_BSD_USER_INTERRUPT;
                        ring->irq_get = gen5_ring_get_irq;
                        ring->irq_put = gen5_ring_put_irq;
                } else {
                        ring->irq_enable_mask = I915_BSD_USER_INTERRUPT;
                        ring->irq_get = i9xx_ring_get_irq;
                        ring->irq_put = i9xx_ring_put_irq;
                }
                ring->dispatch_execbuffer = i965_dispatch_execbuffer;
        }
        ring->init_hw = init_ring_common;

        return intel_init_ring_buffer(dev, ring);
}

/**
 * Initialize the second BSD ring (eg. Broadwell GT3, Skylake GT3)
 */
int intel_init_bsd2_ring_buffer(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring = &dev_priv->ring[VCS2];

        ring->name = "bsd2 ring";
        ring->id = VCS2;

        ring->write_tail = ring_write_tail;
        ring->mmio_base = GEN8_BSD2_RING_BASE;
        ring->flush = gen6_bsd_ring_flush;
        ring->add_request = gen6_add_request;
        ring->get_seqno = gen6_ring_get_seqno;
        ring->set_seqno = ring_set_seqno;
        ring->irq_enable_mask =
                        GT_RENDER_USER_INTERRUPT << GEN8_VCS2_IRQ_SHIFT;
        ring->irq_get = gen8_ring_get_irq;
        ring->irq_put = gen8_ring_put_irq;
        ring->dispatch_execbuffer =
                        gen8_ring_dispatch_execbuffer;
        if (i915_semaphore_is_enabled(dev)) {
                ring->semaphore.sync_to = gen8_ring_sync;
                ring->semaphore.signal = gen8_xcs_signal;
                GEN8_RING_SEMAPHORE_INIT;
        }
        ring->init_hw = init_ring_common;

        return intel_init_ring_buffer(dev, ring);
}

int intel_init_blt_ring_buffer(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring = &dev_priv->ring[BCS];

        ring->name = "blitter ring";
        ring->id = BCS;

        ring->mmio_base = BLT_RING_BASE;
        ring->write_tail = ring_write_tail;
        ring->flush = gen6_ring_flush;
        ring->add_request = gen6_add_request;
        ring->get_seqno = gen6_ring_get_seqno;
        ring->set_seqno = ring_set_seqno;
        if (INTEL_INFO(dev)->gen >= 8) {
                ring->irq_enable_mask =
                        GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT;
                ring->irq_get = gen8_ring_get_irq;
                ring->irq_put = gen8_ring_put_irq;
                ring->dispatch_execbuffer = gen8_ring_dispatch_execbuffer;
                if (i915_semaphore_is_enabled(dev)) {
                        ring->semaphore.sync_to = gen8_ring_sync;
                        ring->semaphore.signal = gen8_xcs_signal;
                        GEN8_RING_SEMAPHORE_INIT;
                }
        } else {
                ring->irq_enable_mask = GT_BLT_USER_INTERRUPT;
                ring->irq_get = gen6_ring_get_irq;
                ring->irq_put = gen6_ring_put_irq;
                ring->dispatch_execbuffer = gen6_ring_dispatch_execbuffer;
                if (i915_semaphore_is_enabled(dev)) {
                        ring->semaphore.signal = gen6_signal;
                        ring->semaphore.sync_to = gen6_ring_sync;
                        /*
                         * The current semaphore is only applied on pre-gen8
                         * platform.  And there is no VCS2 ring on the pre-gen8
                         * platform. So the semaphore between BCS and VCS2 is
                         * initialized as INVALID.  Gen8 will initialize the
                         * sema between BCS and VCS2 later.
                         */
                        ring->semaphore.mbox.wait[RCS] = MI_SEMAPHORE_SYNC_BR;
                        ring->semaphore.mbox.wait[VCS] = MI_SEMAPHORE_SYNC_BV;
                        ring->semaphore.mbox.wait[BCS] = MI_SEMAPHORE_SYNC_INVALID;
                        ring->semaphore.mbox.wait[VECS] = MI_SEMAPHORE_SYNC_BVE;
                        ring->semaphore.mbox.wait[VCS2] = MI_SEMAPHORE_SYNC_INVALID;
                        ring->semaphore.mbox.signal[RCS] = GEN6_RBSYNC;
                        ring->semaphore.mbox.signal[VCS] = GEN6_VBSYNC;
                        ring->semaphore.mbox.signal[BCS] = GEN6_NOSYNC;
                        ring->semaphore.mbox.signal[VECS] = GEN6_VEBSYNC;
                        ring->semaphore.mbox.signal[VCS2] = GEN6_NOSYNC;
                }
        }
        ring->init_hw = init_ring_common;

        return intel_init_ring_buffer(dev, ring);
}

int intel_init_vebox_ring_buffer(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring = &dev_priv->ring[VECS];

        ring->name = "video enhancement ring";
        ring->id = VECS;

        ring->mmio_base = VEBOX_RING_BASE;
        ring->write_tail = ring_write_tail;
        ring->flush = gen6_ring_flush;
        ring->add_request = gen6_add_request;
        ring->get_seqno = gen6_ring_get_seqno;
        ring->set_seqno = ring_set_seqno;

        if (INTEL_INFO(dev)->gen >= 8) {
                ring->irq_enable_mask =
                        GT_RENDER_USER_INTERRUPT << GEN8_VECS_IRQ_SHIFT;
                ring->irq_get = gen8_ring_get_irq;
                ring->irq_put = gen8_ring_put_irq;
                ring->dispatch_execbuffer = gen8_ring_dispatch_execbuffer;
                if (i915_semaphore_is_enabled(dev)) {
                        ring->semaphore.sync_to = gen8_ring_sync;
                        ring->semaphore.signal = gen8_xcs_signal;
                        GEN8_RING_SEMAPHORE_INIT;
                }
        } else {
                ring->irq_enable_mask = PM_VEBOX_USER_INTERRUPT;
                ring->irq_get = hsw_vebox_get_irq;
                ring->irq_put = hsw_vebox_put_irq;
                ring->dispatch_execbuffer = gen6_ring_dispatch_execbuffer;
                if (i915_semaphore_is_enabled(dev)) {
                        ring->semaphore.sync_to = gen6_ring_sync;
                        ring->semaphore.signal = gen6_signal;
                        ring->semaphore.mbox.wait[RCS] = MI_SEMAPHORE_SYNC_VER;
                        ring->semaphore.mbox.wait[VCS] = MI_SEMAPHORE_SYNC_VEV;
                        ring->semaphore.mbox.wait[BCS] = MI_SEMAPHORE_SYNC_VEB;
                        ring->semaphore.mbox.wait[VECS] = MI_SEMAPHORE_SYNC_INVALID;
                        ring->semaphore.mbox.wait[VCS2] = MI_SEMAPHORE_SYNC_INVALID;
                        ring->semaphore.mbox.signal[RCS] = GEN6_RVESYNC;
                        ring->semaphore.mbox.signal[VCS] = GEN6_VVESYNC;
                        ring->semaphore.mbox.signal[BCS] = GEN6_BVESYNC;
                        ring->semaphore.mbox.signal[VECS] = GEN6_NOSYNC;
                        ring->semaphore.mbox.signal[VCS2] = GEN6_NOSYNC;
                }
        }
        ring->init_hw = init_ring_common;

        return intel_init_ring_buffer(dev, ring);
}

int
intel_ring_flush_all_caches(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *ring = req->ring;
        int ret;

        if (!ring->gpu_caches_dirty)
                return 0;

        ret = ring->flush(req, 0, I915_GEM_GPU_DOMAINS);
        if (ret)
                return ret;

        trace_i915_gem_ring_flush(req, 0, I915_GEM_GPU_DOMAINS);

        ring->gpu_caches_dirty = false;
        return 0;
}

int
intel_ring_invalidate_all_caches(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *ring = req->ring;
        uint32_t flush_domains;
        int ret;

        flush_domains = 0;
        if (ring->gpu_caches_dirty)
                flush_domains = I915_GEM_GPU_DOMAINS;

        ret = ring->flush(req, I915_GEM_GPU_DOMAINS, flush_domains);
        if (ret)
                return ret;

        trace_i915_gem_ring_flush(req, I915_GEM_GPU_DOMAINS, flush_domains);

        ring->gpu_caches_dirty = false;
        return 0;
}

void
intel_stop_ring_buffer(struct intel_engine_cs *ring)
{
        int ret;

        if (!intel_ring_initialized(ring))
                return;

        ret = intel_ring_idle(ring);
        if (ret && !i915_reset_in_progress(&to_i915(ring->dev)->gpu_error))
                DRM_ERROR("failed to quiesce %s whilst cleaning up: %d\n",
                          ring->name, ret);

        stop_ring(ring);
}