drm/i915: fix the __intel_fbc_update() comments

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

/*
 * Copyright © 2014 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.
 */

/**
 * DOC: Frame Buffer Compression (FBC)
 *
 * FBC tries to save memory bandwidth (and so power consumption) by
 * compressing the amount of memory used by the display. It is total
 * transparent to user space and completely handled in the kernel.
 *
 * The benefits of FBC are mostly visible with solid backgrounds and
 * variation-less patterns. It comes from keeping the memory footprint small
 * and having fewer memory pages opened and accessed for refreshing the display.
 *
 * i915 is responsible to reserve stolen memory for FBC and configure its
 * offset on proper registers. The hardware takes care of all
 * compress/decompress. However there are many known cases where we have to
 * forcibly disable it to allow proper screen updates.
 */

#include "intel_drv.h"
#include "i915_drv.h"

static inline bool fbc_supported(struct drm_i915_private *dev_priv)
{
        return dev_priv->fbc.enable_fbc != NULL;
}

static inline bool fbc_on_pipe_a_only(struct drm_i915_private *dev_priv)
{
        return IS_HASWELL(dev_priv) || INTEL_INFO(dev_priv)->gen >= 8;
}

/*
 * In some platforms where the CRTC's x:0/y:0 coordinates doesn't match the
 * frontbuffer's x:0/y:0 coordinates we lie to the hardware about the plane's
 * origin so the x and y offsets can actually fit the registers. As a
 * consequence, the fence doesn't really start exactly at the display plane
 * address we program because it starts at the real start of the buffer, so we
 * have to take this into consideration here.
 */
static unsigned int get_crtc_fence_y_offset(struct intel_crtc *crtc)
{
        return crtc->base.y - crtc->adjusted_y;
}

static void i8xx_fbc_disable(struct drm_i915_private *dev_priv)
{
        u32 fbc_ctl;

        dev_priv->fbc.enabled = false;

        /* Disable compression */
        fbc_ctl = I915_READ(FBC_CONTROL);
        if ((fbc_ctl & FBC_CTL_EN) == 0)
                return;

        fbc_ctl &= ~FBC_CTL_EN;
        I915_WRITE(FBC_CONTROL, fbc_ctl);

        /* Wait for compressing bit to clear */
        if (wait_for((I915_READ(FBC_STATUS) & FBC_STAT_COMPRESSING) == 0, 10)) {
                DRM_DEBUG_KMS("FBC idle timed out\n");
                return;
        }

        DRM_DEBUG_KMS("disabled FBC\n");
}

static void i8xx_fbc_enable(struct intel_crtc *crtc)
{
        struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
        struct drm_framebuffer *fb = crtc->base.primary->fb;
        struct drm_i915_gem_object *obj = intel_fb_obj(fb);
        int cfb_pitch;
        int i;
        u32 fbc_ctl;

        dev_priv->fbc.enabled = true;

        /* Note: fbc.threshold == 1 for i8xx */
        cfb_pitch = dev_priv->fbc.uncompressed_size / FBC_LL_SIZE;
        if (fb->pitches[0] < cfb_pitch)
                cfb_pitch = fb->pitches[0];

        /* FBC_CTL wants 32B or 64B units */
        if (IS_GEN2(dev_priv))
                cfb_pitch = (cfb_pitch / 32) - 1;
        else
                cfb_pitch = (cfb_pitch / 64) - 1;

        /* Clear old tags */
        for (i = 0; i < (FBC_LL_SIZE / 32) + 1; i++)
                I915_WRITE(FBC_TAG(i), 0);

        if (IS_GEN4(dev_priv)) {
                u32 fbc_ctl2;

                /* Set it up... */
                fbc_ctl2 = FBC_CTL_FENCE_DBL | FBC_CTL_IDLE_IMM | FBC_CTL_CPU_FENCE;
                fbc_ctl2 |= FBC_CTL_PLANE(crtc->plane);
                I915_WRITE(FBC_CONTROL2, fbc_ctl2);
                I915_WRITE(FBC_FENCE_OFF, get_crtc_fence_y_offset(crtc));
        }

        /* enable it... */
        fbc_ctl = I915_READ(FBC_CONTROL);
        fbc_ctl &= 0x3fff << FBC_CTL_INTERVAL_SHIFT;
        fbc_ctl |= FBC_CTL_EN | FBC_CTL_PERIODIC;
        if (IS_I945GM(dev_priv))
                fbc_ctl |= FBC_CTL_C3_IDLE; /* 945 needs special SR handling */
        fbc_ctl |= (cfb_pitch & 0xff) << FBC_CTL_STRIDE_SHIFT;
        fbc_ctl |= obj->fence_reg;
        I915_WRITE(FBC_CONTROL, fbc_ctl);

        DRM_DEBUG_KMS("enabled FBC, pitch %d, yoff %d, plane %c\n",
                      cfb_pitch, crtc->base.y, plane_name(crtc->plane));
}

static bool i8xx_fbc_enabled(struct drm_i915_private *dev_priv)
{
        return I915_READ(FBC_CONTROL) & FBC_CTL_EN;
}

static void g4x_fbc_enable(struct intel_crtc *crtc)
{
        struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
        struct drm_framebuffer *fb = crtc->base.primary->fb;
        struct drm_i915_gem_object *obj = intel_fb_obj(fb);
        u32 dpfc_ctl;

        dev_priv->fbc.enabled = true;

        dpfc_ctl = DPFC_CTL_PLANE(crtc->plane) | DPFC_SR_EN;
        if (drm_format_plane_cpp(fb->pixel_format, 0) == 2)
                dpfc_ctl |= DPFC_CTL_LIMIT_2X;
        else
                dpfc_ctl |= DPFC_CTL_LIMIT_1X;
        dpfc_ctl |= DPFC_CTL_FENCE_EN | obj->fence_reg;

        I915_WRITE(DPFC_FENCE_YOFF, get_crtc_fence_y_offset(crtc));

        /* enable it... */
        I915_WRITE(DPFC_CONTROL, dpfc_ctl | DPFC_CTL_EN);

        DRM_DEBUG_KMS("enabled fbc on plane %c\n", plane_name(crtc->plane));
}

static void g4x_fbc_disable(struct drm_i915_private *dev_priv)
{
        u32 dpfc_ctl;

        dev_priv->fbc.enabled = false;

        /* Disable compression */
        dpfc_ctl = I915_READ(DPFC_CONTROL);
        if (dpfc_ctl & DPFC_CTL_EN) {
                dpfc_ctl &= ~DPFC_CTL_EN;
                I915_WRITE(DPFC_CONTROL, dpfc_ctl);

                DRM_DEBUG_KMS("disabled FBC\n");
        }
}

static bool g4x_fbc_enabled(struct drm_i915_private *dev_priv)
{
        return I915_READ(DPFC_CONTROL) & DPFC_CTL_EN;
}

/* This function forces a CFB recompression through the nuke operation. */
static void intel_fbc_recompress(struct drm_i915_private *dev_priv)
{
        I915_WRITE(MSG_FBC_REND_STATE, FBC_REND_NUKE);
        POSTING_READ(MSG_FBC_REND_STATE);
}

static void ilk_fbc_enable(struct intel_crtc *crtc)
{
        struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
        struct drm_framebuffer *fb = crtc->base.primary->fb;
        struct drm_i915_gem_object *obj = intel_fb_obj(fb);
        u32 dpfc_ctl;
        int threshold = dev_priv->fbc.threshold;
        unsigned int y_offset;

        dev_priv->fbc.enabled = true;

        dpfc_ctl = DPFC_CTL_PLANE(crtc->plane);
        if (drm_format_plane_cpp(fb->pixel_format, 0) == 2)
                threshold++;

        switch (threshold) {
        case 4:
        case 3:
                dpfc_ctl |= DPFC_CTL_LIMIT_4X;
                break;
        case 2:
                dpfc_ctl |= DPFC_CTL_LIMIT_2X;
                break;
        case 1:
                dpfc_ctl |= DPFC_CTL_LIMIT_1X;
                break;
        }
        dpfc_ctl |= DPFC_CTL_FENCE_EN;
        if (IS_GEN5(dev_priv))
                dpfc_ctl |= obj->fence_reg;

        y_offset = get_crtc_fence_y_offset(crtc);
        I915_WRITE(ILK_DPFC_FENCE_YOFF, y_offset);
        I915_WRITE(ILK_FBC_RT_BASE, i915_gem_obj_ggtt_offset(obj) | ILK_FBC_RT_VALID);
        /* enable it... */
        I915_WRITE(ILK_DPFC_CONTROL, dpfc_ctl | DPFC_CTL_EN);

        if (IS_GEN6(dev_priv)) {
                I915_WRITE(SNB_DPFC_CTL_SA,
                           SNB_CPU_FENCE_ENABLE | obj->fence_reg);
                I915_WRITE(DPFC_CPU_FENCE_OFFSET, y_offset);
        }

        intel_fbc_recompress(dev_priv);

        DRM_DEBUG_KMS("enabled fbc on plane %c\n", plane_name(crtc->plane));
}

static void ilk_fbc_disable(struct drm_i915_private *dev_priv)
{
        u32 dpfc_ctl;

        dev_priv->fbc.enabled = false;

        /* Disable compression */
        dpfc_ctl = I915_READ(ILK_DPFC_CONTROL);
        if (dpfc_ctl & DPFC_CTL_EN) {
                dpfc_ctl &= ~DPFC_CTL_EN;
                I915_WRITE(ILK_DPFC_CONTROL, dpfc_ctl);

                DRM_DEBUG_KMS("disabled FBC\n");
        }
}

static bool ilk_fbc_enabled(struct drm_i915_private *dev_priv)
{
        return I915_READ(ILK_DPFC_CONTROL) & DPFC_CTL_EN;
}

static void gen7_fbc_enable(struct intel_crtc *crtc)
{
        struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
        struct drm_framebuffer *fb = crtc->base.primary->fb;
        struct drm_i915_gem_object *obj = intel_fb_obj(fb);
        u32 dpfc_ctl;
        int threshold = dev_priv->fbc.threshold;

        dev_priv->fbc.enabled = true;

        dpfc_ctl = 0;
        if (IS_IVYBRIDGE(dev_priv))
                dpfc_ctl |= IVB_DPFC_CTL_PLANE(crtc->plane);

        if (drm_format_plane_cpp(fb->pixel_format, 0) == 2)
                threshold++;

        switch (threshold) {
        case 4:
        case 3:
                dpfc_ctl |= DPFC_CTL_LIMIT_4X;
                break;
        case 2:
                dpfc_ctl |= DPFC_CTL_LIMIT_2X;
                break;
        case 1:
                dpfc_ctl |= DPFC_CTL_LIMIT_1X;
                break;
        }

        dpfc_ctl |= IVB_DPFC_CTL_FENCE_EN;

        if (dev_priv->fbc.false_color)
                dpfc_ctl |= FBC_CTL_FALSE_COLOR;

        if (IS_IVYBRIDGE(dev_priv)) {
                /* WaFbcAsynchFlipDisableFbcQueue:ivb */
                I915_WRITE(ILK_DISPLAY_CHICKEN1,
                           I915_READ(ILK_DISPLAY_CHICKEN1) |
                           ILK_FBCQ_DIS);
        } else if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv)) {
                /* WaFbcAsynchFlipDisableFbcQueue:hsw,bdw */
                I915_WRITE(CHICKEN_PIPESL_1(crtc->pipe),
                           I915_READ(CHICKEN_PIPESL_1(crtc->pipe)) |
                           HSW_FBCQ_DIS);
        }

        I915_WRITE(ILK_DPFC_CONTROL, dpfc_ctl | DPFC_CTL_EN);

        I915_WRITE(SNB_DPFC_CTL_SA,
                   SNB_CPU_FENCE_ENABLE | obj->fence_reg);
        I915_WRITE(DPFC_CPU_FENCE_OFFSET, get_crtc_fence_y_offset(crtc));

        intel_fbc_recompress(dev_priv);

        DRM_DEBUG_KMS("enabled fbc on plane %c\n", plane_name(crtc->plane));
}

/**
 * intel_fbc_enabled - Is FBC enabled?
 * @dev_priv: i915 device instance
 *
 * This function is used to verify the current state of FBC.
 * FIXME: This should be tracked in the plane config eventually
 *        instead of queried at runtime for most callers.
 */
bool intel_fbc_enabled(struct drm_i915_private *dev_priv)
{
        return dev_priv->fbc.enabled;
}

static void intel_fbc_enable(struct intel_crtc *crtc,
                             const struct drm_framebuffer *fb)
{
        struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;

        dev_priv->fbc.enable_fbc(crtc);

        dev_priv->fbc.crtc = crtc;
        dev_priv->fbc.fb_id = fb->base.id;
        dev_priv->fbc.y = crtc->base.y;
}

static void intel_fbc_work_fn(struct work_struct *__work)
{
        struct intel_fbc_work *work =
                container_of(to_delayed_work(__work),
                             struct intel_fbc_work, work);
        struct drm_i915_private *dev_priv = work->crtc->base.dev->dev_private;
        struct drm_framebuffer *crtc_fb = work->crtc->base.primary->fb;

        mutex_lock(&dev_priv->fbc.lock);
        if (work == dev_priv->fbc.fbc_work) {
                /* Double check that we haven't switched fb without cancelling
                 * the prior work.
                 */
                if (crtc_fb == work->fb)
                        intel_fbc_enable(work->crtc, work->fb);

                dev_priv->fbc.fbc_work = NULL;
        }
        mutex_unlock(&dev_priv->fbc.lock);

        kfree(work);
}

static void intel_fbc_cancel_work(struct drm_i915_private *dev_priv)
{
        WARN_ON(!mutex_is_locked(&dev_priv->fbc.lock));

        if (dev_priv->fbc.fbc_work == NULL)
                return;

        DRM_DEBUG_KMS("cancelling pending FBC enable\n");

        /* Synchronisation is provided by struct_mutex and checking of
         * dev_priv->fbc.fbc_work, so we can perform the cancellation
         * entirely asynchronously.
         */
        if (cancel_delayed_work(&dev_priv->fbc.fbc_work->work))
                /* tasklet was killed before being run, clean up */
                kfree(dev_priv->fbc.fbc_work);

        /* Mark the work as no longer wanted so that if it does
         * wake-up (because the work was already running and waiting
         * for our mutex), it will discover that is no longer
         * necessary to run.
         */
        dev_priv->fbc.fbc_work = NULL;
}

static void intel_fbc_schedule_enable(struct intel_crtc *crtc)
{
        struct intel_fbc_work *work;
        struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;

        WARN_ON(!mutex_is_locked(&dev_priv->fbc.lock));

        intel_fbc_cancel_work(dev_priv);

        work = kzalloc(sizeof(*work), GFP_KERNEL);
        if (work == NULL) {
                DRM_ERROR("Failed to allocate FBC work structure\n");
                intel_fbc_enable(crtc, crtc->base.primary->fb);
                return;
        }

        work->crtc = crtc;
        work->fb = crtc->base.primary->fb;
        INIT_DELAYED_WORK(&work->work, intel_fbc_work_fn);

        dev_priv->fbc.fbc_work = work;

        /* Delay the actual enabling to let pageflipping cease and the
         * display to settle before starting the compression. Note that
         * this delay also serves a second purpose: it allows for a
         * vblank to pass after disabling the FBC before we attempt
         * to modify the control registers.
         *
         * A more complicated solution would involve tracking vblanks
         * following the termination of the page-flipping sequence
         * and indeed performing the enable as a co-routine and not
         * waiting synchronously upon the vblank.
         *
         * WaFbcWaitForVBlankBeforeEnable:ilk,snb
         */
        schedule_delayed_work(&work->work, msecs_to_jiffies(50));
}

static void __intel_fbc_disable(struct drm_i915_private *dev_priv)
{
        WARN_ON(!mutex_is_locked(&dev_priv->fbc.lock));

        intel_fbc_cancel_work(dev_priv);

        dev_priv->fbc.disable_fbc(dev_priv);
        dev_priv->fbc.crtc = NULL;
}

/**
 * intel_fbc_disable - disable FBC
 * @dev_priv: i915 device instance
 *
 * This function disables FBC.
 */
void intel_fbc_disable(struct drm_i915_private *dev_priv)
{
        if (!fbc_supported(dev_priv))
                return;

        mutex_lock(&dev_priv->fbc.lock);
        __intel_fbc_disable(dev_priv);
        mutex_unlock(&dev_priv->fbc.lock);
}

/*
 * intel_fbc_disable_crtc - disable FBC if it's associated with crtc
 * @crtc: the CRTC
 *
 * This function disables FBC if it's associated with the provided CRTC.
 */
void intel_fbc_disable_crtc(struct intel_crtc *crtc)
{
        struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;

        if (!fbc_supported(dev_priv))
                return;

        mutex_lock(&dev_priv->fbc.lock);
        if (dev_priv->fbc.crtc == crtc)
                __intel_fbc_disable(dev_priv);
        mutex_unlock(&dev_priv->fbc.lock);
}

static void set_no_fbc_reason(struct drm_i915_private *dev_priv,
                              const char *reason)
{
        if (dev_priv->fbc.no_fbc_reason == reason)
                return;

        dev_priv->fbc.no_fbc_reason = reason;
        DRM_DEBUG_KMS("Disabling FBC: %s\n", reason);
}

static bool crtc_is_valid(struct intel_crtc *crtc)
{
        struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;

        if (fbc_on_pipe_a_only(dev_priv) && crtc->pipe != PIPE_A)
                return false;

        if (!intel_crtc_active(&crtc->base))
                return false;

        if (!to_intel_plane_state(crtc->base.primary->state)->visible)
                return false;

        return true;
}

static struct drm_crtc *intel_fbc_find_crtc(struct drm_i915_private *dev_priv)
{
        struct drm_crtc *crtc = NULL, *tmp_crtc;
        enum pipe pipe;

        for_each_pipe(dev_priv, pipe) {
                tmp_crtc = dev_priv->pipe_to_crtc_mapping[pipe];

                if (crtc_is_valid(to_intel_crtc(tmp_crtc)))
                        crtc = tmp_crtc;
        }

        if (!crtc)
                return NULL;

        return crtc;
}

static bool multiple_pipes_ok(struct drm_i915_private *dev_priv)
{
        enum pipe pipe;
        int n_pipes = 0;
        struct drm_crtc *crtc;

        if (INTEL_INFO(dev_priv)->gen > 4)
                return true;

        for_each_pipe(dev_priv, pipe) {
                crtc = dev_priv->pipe_to_crtc_mapping[pipe];

                if (intel_crtc_active(crtc) &&
                    to_intel_plane_state(crtc->primary->state)->visible)
                        n_pipes++;
        }

        return (n_pipes < 2);
}

static int find_compression_threshold(struct drm_i915_private *dev_priv,
                                      struct drm_mm_node *node,
                                      int size,
                                      int fb_cpp)
{
        int compression_threshold = 1;
        int ret;
        u64 end;

        /* The FBC hardware for BDW/SKL doesn't have access to the stolen
         * reserved range size, so it always assumes the maximum (8mb) is used.
         * If we enable FBC using a CFB on that memory range we'll get FIFO
         * underruns, even if that range is not reserved by the BIOS. */
        if (IS_BROADWELL(dev_priv) ||
            IS_SKYLAKE(dev_priv) || IS_KABYLAKE(dev_priv))
                end = dev_priv->gtt.stolen_size - 8 * 1024 * 1024;
        else
                end = dev_priv->gtt.stolen_usable_size;

        /* HACK: This code depends on what we will do in *_enable_fbc. If that
         * code changes, this code needs to change as well.
         *
         * The enable_fbc code will attempt to use one of our 2 compression
         * thresholds, therefore, in that case, we only have 1 resort.
         */

        /* Try to over-allocate to reduce reallocations and fragmentation. */
        ret = i915_gem_stolen_insert_node_in_range(dev_priv, node, size <<= 1,
                                                   4096, 0, end);
        if (ret == 0)
                return compression_threshold;

again:
        /* HW's ability to limit the CFB is 1:4 */
        if (compression_threshold > 4 ||
            (fb_cpp == 2 && compression_threshold == 2))
                return 0;

        ret = i915_gem_stolen_insert_node_in_range(dev_priv, node, size >>= 1,
                                                   4096, 0, end);
        if (ret && INTEL_INFO(dev_priv)->gen <= 4) {
                return 0;
        } else if (ret) {
                compression_threshold <<= 1;
                goto again;
        } else {
                return compression_threshold;
        }
}

static int intel_fbc_alloc_cfb(struct drm_i915_private *dev_priv, int size,
                               int fb_cpp)
{
        struct drm_mm_node *uninitialized_var(compressed_llb);
        int ret;

        ret = find_compression_threshold(dev_priv, &dev_priv->fbc.compressed_fb,
                                         size, fb_cpp);
        if (!ret)
                goto err_llb;
        else if (ret > 1) {
                DRM_INFO("Reducing the compressed framebuffer size. This may lead to less power savings than a non-reduced-size. Try to increase stolen memory size if available in BIOS.\n");

        }

        dev_priv->fbc.threshold = ret;

        if (INTEL_INFO(dev_priv)->gen >= 5)
                I915_WRITE(ILK_DPFC_CB_BASE, dev_priv->fbc.compressed_fb.start);
        else if (IS_GM45(dev_priv)) {
                I915_WRITE(DPFC_CB_BASE, dev_priv->fbc.compressed_fb.start);
        } else {
                compressed_llb = kzalloc(sizeof(*compressed_llb), GFP_KERNEL);
                if (!compressed_llb)
                        goto err_fb;

                ret = i915_gem_stolen_insert_node(dev_priv, compressed_llb,
                                                  4096, 4096);
                if (ret)
                        goto err_fb;

                dev_priv->fbc.compressed_llb = compressed_llb;

                I915_WRITE(FBC_CFB_BASE,
                           dev_priv->mm.stolen_base + dev_priv->fbc.compressed_fb.start);
                I915_WRITE(FBC_LL_BASE,
                           dev_priv->mm.stolen_base + compressed_llb->start);
        }

        dev_priv->fbc.uncompressed_size = size;

        DRM_DEBUG_KMS("reserved %llu bytes of contiguous stolen space for FBC, threshold: %d\n",
                      dev_priv->fbc.compressed_fb.size,
                      dev_priv->fbc.threshold);

        return 0;

err_fb:
        kfree(compressed_llb);
        i915_gem_stolen_remove_node(dev_priv, &dev_priv->fbc.compressed_fb);
err_llb:
        pr_info_once("drm: not enough stolen space for compressed buffer (need %d more bytes), disabling. Hint: you may be able to increase stolen memory size in the BIOS to avoid this.\n", size);
        return -ENOSPC;
}

static void __intel_fbc_cleanup_cfb(struct drm_i915_private *dev_priv)
{
        if (dev_priv->fbc.uncompressed_size == 0)
                return;

        i915_gem_stolen_remove_node(dev_priv, &dev_priv->fbc.compressed_fb);

        if (dev_priv->fbc.compressed_llb) {
                i915_gem_stolen_remove_node(dev_priv,
                                            dev_priv->fbc.compressed_llb);
                kfree(dev_priv->fbc.compressed_llb);
        }

        dev_priv->fbc.uncompressed_size = 0;
}

void intel_fbc_cleanup_cfb(struct drm_i915_private *dev_priv)
{
        if (!fbc_supported(dev_priv))
                return;

        mutex_lock(&dev_priv->fbc.lock);
        __intel_fbc_cleanup_cfb(dev_priv);
        mutex_unlock(&dev_priv->fbc.lock);
}

/*
 * For SKL+, the plane source size used by the hardware is based on the value we
 * write to the PLANE_SIZE register. For BDW-, the hardware looks at the value
 * we wrote to PIPESRC.
 */
static void intel_fbc_get_plane_source_size(struct intel_crtc *crtc,
                                            int *width, int *height)
{
        struct intel_plane_state *plane_state =
                        to_intel_plane_state(crtc->base.primary->state);
        int w, h;

        if (intel_rotation_90_or_270(plane_state->base.rotation)) {
                w = drm_rect_height(&plane_state->src) >> 16;
                h = drm_rect_width(&plane_state->src) >> 16;
        } else {
                w = drm_rect_width(&plane_state->src) >> 16;
                h = drm_rect_height(&plane_state->src) >> 16;
        }

        if (width)
                *width = w;
        if (height)
                *height = h;
}

static int intel_fbc_calculate_cfb_size(struct intel_crtc *crtc)
{
        struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
        struct drm_framebuffer *fb = crtc->base.primary->fb;
        int lines;

        intel_fbc_get_plane_source_size(crtc, NULL, &lines);
        if (INTEL_INFO(dev_priv)->gen >= 7)
                lines = min(lines, 2048);

        return lines * fb->pitches[0];
}

static int intel_fbc_setup_cfb(struct intel_crtc *crtc)
{
        struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
        struct drm_framebuffer *fb = crtc->base.primary->fb;
        int size, cpp;

        size = intel_fbc_calculate_cfb_size(crtc);
        cpp = drm_format_plane_cpp(fb->pixel_format, 0);

        if (size <= dev_priv->fbc.uncompressed_size)
                return 0;

        /* Release any current block */
        __intel_fbc_cleanup_cfb(dev_priv);

        return intel_fbc_alloc_cfb(dev_priv, size, cpp);
}

static bool stride_is_valid(struct drm_i915_private *dev_priv,
                            unsigned int stride)
{
        /* These should have been caught earlier. */
        WARN_ON(stride < 512);
        WARN_ON((stride & (64 - 1)) != 0);

        /* Below are the additional FBC restrictions. */

        if (IS_GEN2(dev_priv) || IS_GEN3(dev_priv))
                return stride == 4096 || stride == 8192;

        if (IS_GEN4(dev_priv) && !IS_G4X(dev_priv) && stride < 2048)
                return false;

        if (stride > 16384)
                return false;

        return true;
}

static bool pixel_format_is_valid(struct drm_framebuffer *fb)
{
        struct drm_device *dev = fb->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        switch (fb->pixel_format) {
        case DRM_FORMAT_XRGB8888:
        case DRM_FORMAT_XBGR8888:
                return true;
        case DRM_FORMAT_XRGB1555:
        case DRM_FORMAT_RGB565:
                /* 16bpp not supported on gen2 */
                if (IS_GEN2(dev))
                        return false;
                /* WaFbcOnly1to1Ratio:ctg */
                if (IS_G4X(dev_priv))
                        return false;
                return true;
        default:
                return false;
        }
}

/*
 * For some reason, the hardware tracking starts looking at whatever we
 * programmed as the display plane base address register. It does not look at
 * the X and Y offset registers. That's why we look at the crtc->adjusted{x,y}
 * variables instead of just looking at the pipe/plane size.
 */
static bool intel_fbc_hw_tracking_covers_screen(struct intel_crtc *crtc)
{
        struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
        unsigned int effective_w, effective_h, max_w, max_h;

        if (INTEL_INFO(dev_priv)->gen >= 8 || IS_HASWELL(dev_priv)) {
                max_w = 4096;
                max_h = 4096;
        } else if (IS_G4X(dev_priv) || INTEL_INFO(dev_priv)->gen >= 5) {
                max_w = 4096;
                max_h = 2048;
        } else {
                max_w = 2048;
                max_h = 1536;
        }

        intel_fbc_get_plane_source_size(crtc, &effective_w, &effective_h);
        effective_w += crtc->adjusted_x;
        effective_h += crtc->adjusted_y;

        return effective_w <= max_w && effective_h <= max_h;
}

/**
 * __intel_fbc_update - enable/disable FBC as needed, unlocked
 * @dev_priv: i915 device instance
 *
 * This function completely reevaluates the status of FBC, then enables,
 * disables or maintains it on the same state.
 */
static void __intel_fbc_update(struct drm_i915_private *dev_priv)
{
        struct drm_crtc *drm_crtc = NULL;
        struct intel_crtc *crtc;
        struct drm_framebuffer *fb;
        struct drm_i915_gem_object *obj;
        const struct drm_display_mode *adjusted_mode;

        WARN_ON(!mutex_is_locked(&dev_priv->fbc.lock));

        if (intel_vgpu_active(dev_priv->dev))
                i915.enable_fbc = 0;

        if (i915.enable_fbc < 0) {
                set_no_fbc_reason(dev_priv, "disabled per chip default");
                goto out_disable;
        }

        if (!i915.enable_fbc) {
                set_no_fbc_reason(dev_priv, "disabled per module param");
                goto out_disable;
        }

        drm_crtc = intel_fbc_find_crtc(dev_priv);
        if (!drm_crtc) {
                set_no_fbc_reason(dev_priv, "no output");
                goto out_disable;
        }

        if (!multiple_pipes_ok(dev_priv)) {
                set_no_fbc_reason(dev_priv, "more than one pipe active");
                goto out_disable;
        }

        crtc = to_intel_crtc(drm_crtc);
        fb = crtc->base.primary->fb;
        obj = intel_fb_obj(fb);
        adjusted_mode = &crtc->config->base.adjusted_mode;

        if ((adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE) ||
            (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)) {
                set_no_fbc_reason(dev_priv, "incompatible mode");
                goto out_disable;
        }

        if (!intel_fbc_hw_tracking_covers_screen(crtc)) {
                set_no_fbc_reason(dev_priv, "mode too large for compression");
                goto out_disable;
        }

        if ((INTEL_INFO(dev_priv)->gen < 4 || HAS_DDI(dev_priv)) &&
            crtc->plane != PLANE_A) {
                set_no_fbc_reason(dev_priv, "FBC unsupported on plane");
                goto out_disable;
        }

        /* The use of a CPU fence is mandatory in order to detect writes
         * by the CPU to the scanout and trigger updates to the FBC.
         */
        if (obj->tiling_mode != I915_TILING_X ||
            obj->fence_reg == I915_FENCE_REG_NONE) {
                set_no_fbc_reason(dev_priv, "framebuffer not tiled or fenced");
                goto out_disable;
        }
        if (INTEL_INFO(dev_priv)->gen <= 4 && !IS_G4X(dev_priv) &&
            crtc->base.primary->state->rotation != BIT(DRM_ROTATE_0)) {
                set_no_fbc_reason(dev_priv, "rotation unsupported");
                goto out_disable;
        }

        if (!stride_is_valid(dev_priv, fb->pitches[0])) {
                set_no_fbc_reason(dev_priv, "framebuffer stride not supported");
                goto out_disable;
        }

        if (!pixel_format_is_valid(fb)) {
                set_no_fbc_reason(dev_priv, "pixel format is invalid");
                goto out_disable;
        }

        /* If the kernel debugger is active, always disable compression */
        if (in_dbg_master()) {
                set_no_fbc_reason(dev_priv, "Kernel debugger is active");
                goto out_disable;
        }

        /* WaFbcExceedCdClockThreshold:hsw,bdw */
        if ((IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv)) &&
            ilk_pipe_pixel_rate(crtc->config) >=
            dev_priv->cdclk_freq * 95 / 100) {
                set_no_fbc_reason(dev_priv, "pixel rate is too big");
                goto out_disable;
        }

        if (intel_fbc_setup_cfb(crtc)) {
                set_no_fbc_reason(dev_priv, "not enough stolen memory");
                goto out_disable;
        }

        /* If the scanout has not changed, don't modify the FBC settings.
         * Note that we make the fundamental assumption that the fb->obj
         * cannot be unpinned (and have its GTT offset and fence revoked)
         * without first being decoupled from the scanout and FBC disabled.
         */
        if (dev_priv->fbc.crtc == crtc &&
            dev_priv->fbc.fb_id == fb->base.id &&
            dev_priv->fbc.y == crtc->base.y)
                return;

        if (intel_fbc_enabled(dev_priv)) {
                /* We update FBC along two paths, after changing fb/crtc
                 * configuration (modeswitching) and after page-flipping
                 * finishes. For the latter, we know that not only did
                 * we disable the FBC at the start of the page-flip
                 * sequence, but also more than one vblank has passed.
                 *
                 * For the former case of modeswitching, it is possible
                 * to switch between two FBC valid configurations
                 * instantaneously so we do need to disable the FBC
                 * before we can modify its control registers. We also
                 * have to wait for the next vblank for that to take
                 * effect. However, since we delay enabling FBC we can
                 * assume that a vblank has passed since disabling and
                 * that we can safely alter the registers in the deferred
                 * callback.
                 *
                 * In the scenario that we go from a valid to invalid
                 * and then back to valid FBC configuration we have
                 * no strict enforcement that a vblank occurred since
                 * disabling the FBC. However, along all current pipe
                 * disabling paths we do need to wait for a vblank at
                 * some point. And we wait before enabling FBC anyway.
                 */
                DRM_DEBUG_KMS("disabling active FBC for update\n");
                __intel_fbc_disable(dev_priv);
        }

        intel_fbc_schedule_enable(crtc);
        dev_priv->fbc.no_fbc_reason = "FBC enabled (not necessarily active)";
        return;

out_disable:
        /* Multiple disables should be harmless */
        if (intel_fbc_enabled(dev_priv)) {
                DRM_DEBUG_KMS("unsupported config, disabling FBC\n");
                __intel_fbc_disable(dev_priv);
        }
        __intel_fbc_cleanup_cfb(dev_priv);
}

/*
 * intel_fbc_update - enable/disable FBC as needed
 * @dev_priv: i915 device instance
 *
 * This function reevaluates the overall state and enables or disables FBC.
 */
void intel_fbc_update(struct drm_i915_private *dev_priv)
{
        if (!fbc_supported(dev_priv))
                return;

        mutex_lock(&dev_priv->fbc.lock);
        __intel_fbc_update(dev_priv);
        mutex_unlock(&dev_priv->fbc.lock);
}

void intel_fbc_invalidate(struct drm_i915_private *dev_priv,
                          unsigned int frontbuffer_bits,
                          enum fb_op_origin origin)
{
        unsigned int fbc_bits;

        if (!fbc_supported(dev_priv))
                return;

        if (origin == ORIGIN_GTT)
                return;

        mutex_lock(&dev_priv->fbc.lock);

        if (dev_priv->fbc.enabled)
                fbc_bits = INTEL_FRONTBUFFER_PRIMARY(dev_priv->fbc.crtc->pipe);
        else if (dev_priv->fbc.fbc_work)
                fbc_bits = INTEL_FRONTBUFFER_PRIMARY(
                                        dev_priv->fbc.fbc_work->crtc->pipe);
        else
                fbc_bits = dev_priv->fbc.possible_framebuffer_bits;

        dev_priv->fbc.busy_bits |= (fbc_bits & frontbuffer_bits);

        if (dev_priv->fbc.busy_bits)
                __intel_fbc_disable(dev_priv);

        mutex_unlock(&dev_priv->fbc.lock);
}

void intel_fbc_flush(struct drm_i915_private *dev_priv,
                     unsigned int frontbuffer_bits, enum fb_op_origin origin)
{
        if (!fbc_supported(dev_priv))
                return;

        if (origin == ORIGIN_GTT)
                return;

        mutex_lock(&dev_priv->fbc.lock);

        dev_priv->fbc.busy_bits &= ~frontbuffer_bits;

        if (!dev_priv->fbc.busy_bits) {
                __intel_fbc_disable(dev_priv);
                __intel_fbc_update(dev_priv);
        }

        mutex_unlock(&dev_priv->fbc.lock);
}

/**
 * intel_fbc_init - Initialize FBC
 * @dev_priv: the i915 device
 *
 * This function might be called during PM init process.
 */
void intel_fbc_init(struct drm_i915_private *dev_priv)
{
        enum pipe pipe;

        mutex_init(&dev_priv->fbc.lock);

        if (!HAS_FBC(dev_priv)) {
                dev_priv->fbc.enabled = false;
                dev_priv->fbc.no_fbc_reason = "unsupported by this chipset";
                return;
        }

        for_each_pipe(dev_priv, pipe) {
                dev_priv->fbc.possible_framebuffer_bits |=
                                INTEL_FRONTBUFFER_PRIMARY(pipe);

                if (fbc_on_pipe_a_only(dev_priv))
                        break;
        }

        if (INTEL_INFO(dev_priv)->gen >= 7) {
                dev_priv->fbc.fbc_enabled = ilk_fbc_enabled;
                dev_priv->fbc.enable_fbc = gen7_fbc_enable;
                dev_priv->fbc.disable_fbc = ilk_fbc_disable;
        } else if (INTEL_INFO(dev_priv)->gen >= 5) {
                dev_priv->fbc.fbc_enabled = ilk_fbc_enabled;
                dev_priv->fbc.enable_fbc = ilk_fbc_enable;
                dev_priv->fbc.disable_fbc = ilk_fbc_disable;
        } else if (IS_GM45(dev_priv)) {
                dev_priv->fbc.fbc_enabled = g4x_fbc_enabled;
                dev_priv->fbc.enable_fbc = g4x_fbc_enable;
                dev_priv->fbc.disable_fbc = g4x_fbc_disable;
        } else {
                dev_priv->fbc.fbc_enabled = i8xx_fbc_enabled;
                dev_priv->fbc.enable_fbc = i8xx_fbc_enable;
                dev_priv->fbc.disable_fbc = i8xx_fbc_disable;

                /* This value was pulled out of someone's hat */
                I915_WRITE(FBC_CONTROL, 500 << FBC_CTL_INTERVAL_SHIFT);
        }

        dev_priv->fbc.enabled = dev_priv->fbc.fbc_enabled(dev_priv);
}