Merge branch 'writable_limits' of git://decibel.fi.muni.cz/~xslaby/linux

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

/*
 * Copyright © 2006-2007 Intel Corporation
 * Copyright (c) 2006 Dave Airlie <airlied@linux.ie>
 *
 * 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>
 *      Dave Airlie <airlied@linux.ie>
 *      Jesse Barnes <jesse.barnes@intel.com>
 */

#include <acpi/button.h>
#include <linux/dmi.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include "drmP.h"
#include "drm.h"
#include "drm_crtc.h"
#include "drm_edid.h"
#include "intel_drv.h"
#include "i915_drm.h"
#include "i915_drv.h"
#include <linux/acpi.h>

/* Private structure for the integrated LVDS support */
struct intel_lvds_priv {
        int fitting_mode;
        u32 pfit_control;
        u32 pfit_pgm_ratios;
};

/**
 * Sets the backlight level.
 *
 * \param level backlight level, from 0 to intel_lvds_get_max_backlight().
 */
static void intel_lvds_set_backlight(struct drm_device *dev, int level)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 blc_pwm_ctl, reg;

        if (HAS_PCH_SPLIT(dev))
                reg = BLC_PWM_CPU_CTL;
        else
                reg = BLC_PWM_CTL;

        blc_pwm_ctl = I915_READ(reg) & ~BACKLIGHT_DUTY_CYCLE_MASK;
        I915_WRITE(reg, (blc_pwm_ctl |
                                 (level << BACKLIGHT_DUTY_CYCLE_SHIFT)));
}

/**
 * Returns the maximum level of the backlight duty cycle field.
 */
static u32 intel_lvds_get_max_backlight(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 reg;

        if (HAS_PCH_SPLIT(dev))
                reg = BLC_PWM_PCH_CTL2;
        else
                reg = BLC_PWM_CTL;

        return ((I915_READ(reg) & BACKLIGHT_MODULATION_FREQ_MASK) >>
                BACKLIGHT_MODULATION_FREQ_SHIFT) * 2;
}

/**
 * Sets the power state for the panel.
 */
static void intel_lvds_set_power(struct drm_device *dev, bool on)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 pp_status, ctl_reg, status_reg, lvds_reg;

        if (HAS_PCH_SPLIT(dev)) {
                ctl_reg = PCH_PP_CONTROL;
                status_reg = PCH_PP_STATUS;
                lvds_reg = PCH_LVDS;
        } else {
                ctl_reg = PP_CONTROL;
                status_reg = PP_STATUS;
                lvds_reg = LVDS;
        }

        if (on) {
                I915_WRITE(lvds_reg, I915_READ(lvds_reg) | LVDS_PORT_EN);
                POSTING_READ(lvds_reg);

                I915_WRITE(ctl_reg, I915_READ(ctl_reg) |
                           POWER_TARGET_ON);
                do {
                        pp_status = I915_READ(status_reg);
                } while ((pp_status & PP_ON) == 0);

                intel_lvds_set_backlight(dev, dev_priv->backlight_duty_cycle);
        } else {
                intel_lvds_set_backlight(dev, 0);

                I915_WRITE(ctl_reg, I915_READ(ctl_reg) &
                           ~POWER_TARGET_ON);
                do {
                        pp_status = I915_READ(status_reg);
                } while (pp_status & PP_ON);

                I915_WRITE(lvds_reg, I915_READ(lvds_reg) & ~LVDS_PORT_EN);
                POSTING_READ(lvds_reg);
        }
}

static void intel_lvds_dpms(struct drm_encoder *encoder, int mode)
{
        struct drm_device *dev = encoder->dev;

        if (mode == DRM_MODE_DPMS_ON)
                intel_lvds_set_power(dev, true);
        else
                intel_lvds_set_power(dev, false);

        /* XXX: We never power down the LVDS pairs. */
}

static int intel_lvds_mode_valid(struct drm_connector *connector,
                                 struct drm_display_mode *mode)
{
        struct drm_device *dev = connector->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_display_mode *fixed_mode = dev_priv->panel_fixed_mode;

        if (fixed_mode) {
                if (mode->hdisplay > fixed_mode->hdisplay)
                        return MODE_PANEL;
                if (mode->vdisplay > fixed_mode->vdisplay)
                        return MODE_PANEL;
        }

        return MODE_OK;
}

static void
centre_horizontally(struct drm_display_mode *mode,
                    int width)
{
        u32 border, sync_pos, blank_width, sync_width;

        /* keep the hsync and hblank widths constant */
        sync_width = mode->crtc_hsync_end - mode->crtc_hsync_start;
        blank_width = mode->crtc_hblank_end - mode->crtc_hblank_start;
        sync_pos = (blank_width - sync_width + 1) / 2;

        border = (mode->hdisplay - width + 1) / 2;
        border += border & 1; /* make the border even */

        mode->crtc_hdisplay = width;
        mode->crtc_hblank_start = width + border;
        mode->crtc_hblank_end = mode->crtc_hblank_start + blank_width;

        mode->crtc_hsync_start = mode->crtc_hblank_start + sync_pos;
        mode->crtc_hsync_end = mode->crtc_hsync_start + sync_width;
}

static void
centre_vertically(struct drm_display_mode *mode,
                  int height)
{
        u32 border, sync_pos, blank_width, sync_width;

        /* keep the vsync and vblank widths constant */
        sync_width = mode->crtc_vsync_end - mode->crtc_vsync_start;
        blank_width = mode->crtc_vblank_end - mode->crtc_vblank_start;
        sync_pos = (blank_width - sync_width + 1) / 2;

        border = (mode->vdisplay - height + 1) / 2;

        mode->crtc_vdisplay = height;
        mode->crtc_vblank_start = height + border;
        mode->crtc_vblank_end = mode->crtc_vblank_start + blank_width;

        mode->crtc_vsync_start = mode->crtc_vblank_start + sync_pos;
        mode->crtc_vsync_end = mode->crtc_vsync_start + sync_width;
}

static inline u32 panel_fitter_scaling(u32 source, u32 target)
{
        /*
         * Floating point operation is not supported. So the FACTOR
         * is defined, which can avoid the floating point computation
         * when calculating the panel ratio.
         */
#define ACCURACY 12
#define FACTOR (1 << ACCURACY)
        u32 ratio = source * FACTOR / target;
        return (FACTOR * ratio + FACTOR/2) / FACTOR;
}

static bool intel_lvds_mode_fixup(struct drm_encoder *encoder,
                                  struct drm_display_mode *mode,
                                  struct drm_display_mode *adjusted_mode)
{
        struct drm_device *dev = encoder->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_crtc *intel_crtc = to_intel_crtc(encoder->crtc);
        struct drm_encoder *tmp_encoder;
        struct intel_encoder *intel_encoder = enc_to_intel_encoder(encoder);
        struct intel_lvds_priv *lvds_priv = intel_encoder->dev_priv;
        u32 pfit_control = 0, pfit_pgm_ratios = 0, border = 0;

        /* Should never happen!! */
        if (!IS_I965G(dev) && intel_crtc->pipe == 0) {
                DRM_ERROR("Can't support LVDS on pipe A\n");
                return false;
        }

        /* Should never happen!! */
        list_for_each_entry(tmp_encoder, &dev->mode_config.encoder_list, head) {
                if (tmp_encoder != encoder && tmp_encoder->crtc == encoder->crtc) {
                        DRM_ERROR("Can't enable LVDS and another "
                               "encoder on the same pipe\n");
                        return false;
                }
        }
        /* If we don't have a panel mode, there is nothing we can do */
        if (dev_priv->panel_fixed_mode == NULL)
                return true;
        /*
         * We have timings from the BIOS for the panel, put them in
         * to the adjusted mode.  The CRTC will be set up for this mode,
         * with the panel scaling set up to source from the H/VDisplay
         * of the original mode.
         */
        adjusted_mode->hdisplay = dev_priv->panel_fixed_mode->hdisplay;
        adjusted_mode->hsync_start =
                dev_priv->panel_fixed_mode->hsync_start;
        adjusted_mode->hsync_end =
                dev_priv->panel_fixed_mode->hsync_end;
        adjusted_mode->htotal = dev_priv->panel_fixed_mode->htotal;
        adjusted_mode->vdisplay = dev_priv->panel_fixed_mode->vdisplay;
        adjusted_mode->vsync_start =
                dev_priv->panel_fixed_mode->vsync_start;
        adjusted_mode->vsync_end =
                dev_priv->panel_fixed_mode->vsync_end;
        adjusted_mode->vtotal = dev_priv->panel_fixed_mode->vtotal;
        adjusted_mode->clock = dev_priv->panel_fixed_mode->clock;
        drm_mode_set_crtcinfo(adjusted_mode, CRTC_INTERLACE_HALVE_V);

        /* Make sure pre-965s set dither correctly */
        if (!IS_I965G(dev)) {
                if (dev_priv->panel_wants_dither || dev_priv->lvds_dither)
                        pfit_control |= PANEL_8TO6_DITHER_ENABLE;
        }

        /* Native modes don't need fitting */
        if (adjusted_mode->hdisplay == mode->hdisplay &&
            adjusted_mode->vdisplay == mode->vdisplay)
                goto out;

        /* full screen scale for now */
        if (HAS_PCH_SPLIT(dev))
                goto out;

        /* 965+ wants fuzzy fitting */
        if (IS_I965G(dev))
                pfit_control |= ((intel_crtc->pipe << PFIT_PIPE_SHIFT) |
                                 PFIT_FILTER_FUZZY);

        /*
         * Enable automatic panel scaling for non-native modes so that they fill
         * the screen.  Should be enabled before the pipe is enabled, according
         * to register description and PRM.
         * Change the value here to see the borders for debugging
         */
        if (!HAS_PCH_SPLIT(dev)) {
                I915_WRITE(BCLRPAT_A, 0);
                I915_WRITE(BCLRPAT_B, 0);
        }

        switch (lvds_priv->fitting_mode) {
        case DRM_MODE_SCALE_CENTER:
                /*
                 * For centered modes, we have to calculate border widths &
                 * heights and modify the values programmed into the CRTC.
                 */
                centre_horizontally(adjusted_mode, mode->hdisplay);
                centre_vertically(adjusted_mode, mode->vdisplay);
                border = LVDS_BORDER_ENABLE;
                break;

        case DRM_MODE_SCALE_ASPECT:
                /* Scale but preserve the aspect ratio */
                if (IS_I965G(dev)) {
                        u32 scaled_width = adjusted_mode->hdisplay * mode->vdisplay;
                        u32 scaled_height = mode->hdisplay * adjusted_mode->vdisplay;

                        pfit_control |= PFIT_ENABLE;
                        /* 965+ is easy, it does everything in hw */
                        if (scaled_width > scaled_height)
                                pfit_control |= PFIT_SCALING_PILLAR;
                        else if (scaled_width < scaled_height)
                                pfit_control |= PFIT_SCALING_LETTER;
                        else
                                pfit_control |= PFIT_SCALING_AUTO;
                } else {
                        u32 scaled_width = adjusted_mode->hdisplay * mode->vdisplay;
                        u32 scaled_height = mode->hdisplay * adjusted_mode->vdisplay;
                        /*
                         * For earlier chips we have to calculate the scaling
                         * ratio by hand and program it into the
                         * PFIT_PGM_RATIO register
                         */
                        if (scaled_width > scaled_height) { /* pillar */
                                centre_horizontally(adjusted_mode, scaled_height / mode->vdisplay);

                                border = LVDS_BORDER_ENABLE;
                                if (mode->vdisplay != adjusted_mode->vdisplay) {
                                        u32 bits = panel_fitter_scaling(mode->vdisplay, adjusted_mode->vdisplay);
                                        pfit_pgm_ratios |= (bits << PFIT_HORIZ_SCALE_SHIFT |
                                                            bits << PFIT_VERT_SCALE_SHIFT);
                                        pfit_control |= (PFIT_ENABLE |
                                                         VERT_INTERP_BILINEAR |
                                                         HORIZ_INTERP_BILINEAR);
                                }
                        } else if (scaled_width < scaled_height) { /* letter */
                                centre_vertically(adjusted_mode, scaled_width / mode->hdisplay);

                                border = LVDS_BORDER_ENABLE;
                                if (mode->hdisplay != adjusted_mode->hdisplay) {
                                        u32 bits = panel_fitter_scaling(mode->hdisplay, adjusted_mode->hdisplay);
                                        pfit_pgm_ratios |= (bits << PFIT_HORIZ_SCALE_SHIFT |
                                                            bits << PFIT_VERT_SCALE_SHIFT);
                                        pfit_control |= (PFIT_ENABLE |
                                                         VERT_INTERP_BILINEAR |
                                                         HORIZ_INTERP_BILINEAR);
                                }
                        } else
                                /* Aspects match, Let hw scale both directions */
                                pfit_control |= (PFIT_ENABLE |
                                                 VERT_AUTO_SCALE | HORIZ_AUTO_SCALE |
                                                 VERT_INTERP_BILINEAR |
                                                 HORIZ_INTERP_BILINEAR);
                }
                break;

        case DRM_MODE_SCALE_FULLSCREEN:
                /*
                 * Full scaling, even if it changes the aspect ratio.
                 * Fortunately this is all done for us in hw.
                 */
                pfit_control |= PFIT_ENABLE;
                if (IS_I965G(dev))
                        pfit_control |= PFIT_SCALING_AUTO;
                else
                        pfit_control |= (VERT_AUTO_SCALE | HORIZ_AUTO_SCALE |
                                         VERT_INTERP_BILINEAR |
                                         HORIZ_INTERP_BILINEAR);
                break;

        default:
                break;
        }

out:
        lvds_priv->pfit_control = pfit_control;
        lvds_priv->pfit_pgm_ratios = pfit_pgm_ratios;
        dev_priv->lvds_border_bits = border;

        /*
         * XXX: It would be nice to support lower refresh rates on the
         * panels to reduce power consumption, and perhaps match the
         * user's requested refresh rate.
         */

        return true;
}

static void intel_lvds_prepare(struct drm_encoder *encoder)
{
        struct drm_device *dev = encoder->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 reg;

        if (HAS_PCH_SPLIT(dev))
                reg = BLC_PWM_CPU_CTL;
        else
                reg = BLC_PWM_CTL;

        dev_priv->saveBLC_PWM_CTL = I915_READ(reg);
        dev_priv->backlight_duty_cycle = (dev_priv->saveBLC_PWM_CTL &
                                       BACKLIGHT_DUTY_CYCLE_MASK);

        intel_lvds_set_power(dev, false);
}

static void intel_lvds_commit( struct drm_encoder *encoder)
{
        struct drm_device *dev = encoder->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        if (dev_priv->backlight_duty_cycle == 0)
                dev_priv->backlight_duty_cycle =
                        intel_lvds_get_max_backlight(dev);

        intel_lvds_set_power(dev, true);
}

static void intel_lvds_mode_set(struct drm_encoder *encoder,
                                struct drm_display_mode *mode,
                                struct drm_display_mode *adjusted_mode)
{
        struct drm_device *dev = encoder->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_encoder *intel_encoder = enc_to_intel_encoder(encoder);
        struct intel_lvds_priv *lvds_priv = intel_encoder->dev_priv;

        /*
         * The LVDS pin pair will already have been turned on in the
         * intel_crtc_mode_set since it has a large impact on the DPLL
         * settings.
         */

        if (HAS_PCH_SPLIT(dev))
                return;

        /*
         * Enable automatic panel scaling so that non-native modes fill the
         * screen.  Should be enabled before the pipe is enabled, according to
         * register description and PRM.
         */
        I915_WRITE(PFIT_PGM_RATIOS, lvds_priv->pfit_pgm_ratios);
        I915_WRITE(PFIT_CONTROL, lvds_priv->pfit_control);
}

/**
 * Detect the LVDS connection.
 *
 * Since LVDS doesn't have hotlug, we use the lid as a proxy.  Open means
 * connected and closed means disconnected.  We also send hotplug events as
 * needed, using lid status notification from the input layer.
 */
static enum drm_connector_status intel_lvds_detect(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;
        enum drm_connector_status status = connector_status_connected;

        /* ACPI lid methods were generally unreliable in this generation, so
         * don't even bother.
         */
        if (IS_GEN2(dev) || IS_GEN3(dev))
                return connector_status_connected;

        return status;
}

/**
 * Return the list of DDC modes if available, or the BIOS fixed mode otherwise.
 */
static int intel_lvds_get_modes(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;
        struct drm_encoder *encoder = intel_attached_encoder(connector);
        struct intel_encoder *intel_encoder = enc_to_intel_encoder(encoder);
        struct drm_i915_private *dev_priv = dev->dev_private;
        int ret = 0;

        if (dev_priv->lvds_edid_good) {
                ret = intel_ddc_get_modes(connector, intel_encoder->ddc_bus);

                if (ret)
                        return ret;
        }

        /* Didn't get an EDID, so
         * Set wide sync ranges so we get all modes
         * handed to valid_mode for checking
         */
        connector->display_info.min_vfreq = 0;
        connector->display_info.max_vfreq = 200;
        connector->display_info.min_hfreq = 0;
        connector->display_info.max_hfreq = 200;

        if (dev_priv->panel_fixed_mode != NULL) {
                struct drm_display_mode *mode;

                mode = drm_mode_duplicate(dev, dev_priv->panel_fixed_mode);
                drm_mode_probed_add(connector, mode);

                return 1;
        }

        return 0;
}

static int intel_no_modeset_on_lid_dmi_callback(const struct dmi_system_id *id)
{
        DRM_DEBUG_KMS("Skipping forced modeset for %s\n", id->ident);
        return 1;
}

/* The GPU hangs up on these systems if modeset is performed on LID open */
static const struct dmi_system_id intel_no_modeset_on_lid[] = {
        {
                .callback = intel_no_modeset_on_lid_dmi_callback,
                .ident = "Toshiba Tecra A11",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "TECRA A11"),
                },
        },

        { }     /* terminating entry */
};

/*
 * Lid events. Note the use of 'modeset_on_lid':
 *  - we set it on lid close, and reset it on open
 *  - we use it as a "only once" bit (ie we ignore
 *    duplicate events where it was already properly
 *    set/reset)
 *  - the suspend/resume paths will also set it to
 *    zero, since they restore the mode ("lid open").
 */
static int intel_lid_notify(struct notifier_block *nb, unsigned long val,
                            void *unused)
{
        struct drm_i915_private *dev_priv =
                container_of(nb, struct drm_i915_private, lid_notifier);
        struct drm_device *dev = dev_priv->dev;
        struct drm_connector *connector = dev_priv->int_lvds_connector;

        /*
         * check and update the status of LVDS connector after receiving
         * the LID nofication event.
         */
        if (connector)
                connector->status = connector->funcs->detect(connector);
        /* Don't force modeset on machines where it causes a GPU lockup */
        if (dmi_check_system(intel_no_modeset_on_lid))
                return NOTIFY_OK;
        if (!acpi_lid_open()) {
                dev_priv->modeset_on_lid = 1;
                return NOTIFY_OK;
        }

        if (!dev_priv->modeset_on_lid)
                return NOTIFY_OK;

        dev_priv->modeset_on_lid = 0;

        mutex_lock(&dev->mode_config.mutex);
        drm_helper_resume_force_mode(dev);
        mutex_unlock(&dev->mode_config.mutex);

        return NOTIFY_OK;
}

/**
 * intel_lvds_destroy - unregister and free LVDS structures
 * @connector: connector to free
 *
 * Unregister the DDC bus for this connector then free the driver private
 * structure.
 */
static void intel_lvds_destroy(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        if (dev_priv->lid_notifier.notifier_call)
                acpi_lid_notifier_unregister(&dev_priv->lid_notifier);
        drm_sysfs_connector_remove(connector);
        drm_connector_cleanup(connector);
        kfree(connector);
}

static int intel_lvds_set_property(struct drm_connector *connector,
                                   struct drm_property *property,
                                   uint64_t value)
{
        struct drm_device *dev = connector->dev;

        if (property == dev->mode_config.scaling_mode_property &&
                                connector->encoder) {
                struct drm_crtc *crtc = connector->encoder->crtc;
                struct drm_encoder *encoder = connector->encoder;
                struct intel_encoder *intel_encoder = enc_to_intel_encoder(encoder);
                struct intel_lvds_priv *lvds_priv = intel_encoder->dev_priv;

                if (value == DRM_MODE_SCALE_NONE) {
                        DRM_DEBUG_KMS("no scaling not supported\n");
                        return 0;
                }
                if (lvds_priv->fitting_mode == value) {
                        /* the LVDS scaling property is not changed */
                        return 0;
                }
                lvds_priv->fitting_mode = value;
                if (crtc && crtc->enabled) {
                        /*
                         * If the CRTC is enabled, the display will be changed
                         * according to the new panel fitting mode.
                         */
                        drm_crtc_helper_set_mode(crtc, &crtc->mode,
                                crtc->x, crtc->y, crtc->fb);
                }
        }

        return 0;
}

static const struct drm_encoder_helper_funcs intel_lvds_helper_funcs = {
        .dpms = intel_lvds_dpms,
        .mode_fixup = intel_lvds_mode_fixup,
        .prepare = intel_lvds_prepare,
        .mode_set = intel_lvds_mode_set,
        .commit = intel_lvds_commit,
};

static const struct drm_connector_helper_funcs intel_lvds_connector_helper_funcs = {
        .get_modes = intel_lvds_get_modes,
        .mode_valid = intel_lvds_mode_valid,
        .best_encoder = intel_attached_encoder,
};

static const struct drm_connector_funcs intel_lvds_connector_funcs = {
        .dpms = drm_helper_connector_dpms,
        .detect = intel_lvds_detect,
        .fill_modes = drm_helper_probe_single_connector_modes,
        .set_property = intel_lvds_set_property,
        .destroy = intel_lvds_destroy,
};


static void intel_lvds_enc_destroy(struct drm_encoder *encoder)
{
        struct intel_encoder *intel_encoder = enc_to_intel_encoder(encoder);

        if (intel_encoder->ddc_bus)
                intel_i2c_destroy(intel_encoder->ddc_bus);
        drm_encoder_cleanup(encoder);
        kfree(intel_encoder);
}

static const struct drm_encoder_funcs intel_lvds_enc_funcs = {
        .destroy = intel_lvds_enc_destroy,
};

static int __init intel_no_lvds_dmi_callback(const struct dmi_system_id *id)
{
        DRM_DEBUG_KMS("Skipping LVDS initialization for %s\n", id->ident);
        return 1;
}

/* These systems claim to have LVDS, but really don't */
static const struct dmi_system_id intel_no_lvds[] = {
        {
                .callback = intel_no_lvds_dmi_callback,
                .ident = "Apple Mac Mini (Core series)",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Apple"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Macmini1,1"),
                },
        },
        {
                .callback = intel_no_lvds_dmi_callback,
                .ident = "Apple Mac Mini (Core 2 series)",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Apple"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Macmini2,1"),
                },
        },
        {
                .callback = intel_no_lvds_dmi_callback,
                .ident = "MSI IM-945GSE-A",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "MSI"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "A9830IMS"),
                },
        },
        {
                .callback = intel_no_lvds_dmi_callback,
                .ident = "Dell Studio Hybrid",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Studio Hybrid 140g"),
                },
        },
        {
                .callback = intel_no_lvds_dmi_callback,
                .ident = "AOpen Mini PC",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "AOpen"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "i965GMx-IF"),
                },
        },
        {
                .callback = intel_no_lvds_dmi_callback,
                .ident = "AOpen Mini PC MP915",
                .matches = {
                        DMI_MATCH(DMI_BOARD_VENDOR, "AOpen"),
                        DMI_MATCH(DMI_BOARD_NAME, "i915GMx-F"),
                },
        },
        {
                .callback = intel_no_lvds_dmi_callback,
                .ident = "Aopen i945GTt-VFA",
                .matches = {
                        DMI_MATCH(DMI_PRODUCT_VERSION, "AO00001JW"),
                },
        },
        {
                .callback = intel_no_lvds_dmi_callback,
                .ident = "Clientron U800",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Clientron"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "U800"),
                },
        },

        { }     /* terminating entry */
};

/**
 * intel_find_lvds_downclock - find the reduced downclock for LVDS in EDID
 * @dev: drm device
 * @connector: LVDS connector
 *
 * Find the reduced downclock for LVDS in EDID.
 */
static void intel_find_lvds_downclock(struct drm_device *dev,
                                struct drm_connector *connector)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_display_mode *scan, *panel_fixed_mode;
        int temp_downclock;

        panel_fixed_mode = dev_priv->panel_fixed_mode;
        temp_downclock = panel_fixed_mode->clock;

        mutex_lock(&dev->mode_config.mutex);
        list_for_each_entry(scan, &connector->probed_modes, head) {
                /*
                 * If one mode has the same resolution with the fixed_panel
                 * mode while they have the different refresh rate, it means
                 * that the reduced downclock is found for the LVDS. In such
                 * case we can set the different FPx0/1 to dynamically select
                 * between low and high frequency.
                 */
                if (scan->hdisplay == panel_fixed_mode->hdisplay &&
                        scan->hsync_start == panel_fixed_mode->hsync_start &&
                        scan->hsync_end == panel_fixed_mode->hsync_end &&
                        scan->htotal == panel_fixed_mode->htotal &&
                        scan->vdisplay == panel_fixed_mode->vdisplay &&
                        scan->vsync_start == panel_fixed_mode->vsync_start &&
                        scan->vsync_end == panel_fixed_mode->vsync_end &&
                        scan->vtotal == panel_fixed_mode->vtotal) {
                        if (scan->clock < temp_downclock) {
                                /*
                                 * The downclock is already found. But we
                                 * expect to find the lower downclock.
                                 */
                                temp_downclock = scan->clock;
                        }
                }
        }
        mutex_unlock(&dev->mode_config.mutex);
        if (temp_downclock < panel_fixed_mode->clock &&
            i915_lvds_downclock) {
                /* We found the downclock for LVDS. */
                dev_priv->lvds_downclock_avail = 1;
                dev_priv->lvds_downclock = temp_downclock;
                DRM_DEBUG_KMS("LVDS downclock is found in EDID. "
                                "Normal clock %dKhz, downclock %dKhz\n",
                                panel_fixed_mode->clock, temp_downclock);
        }
        return;
}

/*
 * Enumerate the child dev array parsed from VBT to check whether
 * the LVDS is present.
 * If it is present, return 1.
 * If it is not present, return false.
 * If no child dev is parsed from VBT, it assumes that the LVDS is present.
 * Note: The addin_offset should also be checked for LVDS panel.
 * Only when it is non-zero, it is assumed that it is present.
 */
static int lvds_is_present_in_vbt(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct child_device_config *p_child;
        int i, ret;

        if (!dev_priv->child_dev_num)
                return 1;

        ret = 0;
        for (i = 0; i < dev_priv->child_dev_num; i++) {
                p_child = dev_priv->child_dev + i;
                /*
                 * If the device type is not LFP, continue.
                 * If the device type is 0x22, it is also regarded as LFP.
                 */
                if (p_child->device_type != DEVICE_TYPE_INT_LFP &&
                        p_child->device_type != DEVICE_TYPE_LFP)
                        continue;

                /* The addin_offset should be checked. Only when it is
                 * non-zero, it is regarded as present.
                 */
                if (p_child->addin_offset) {
                        ret = 1;
                        break;
                }
        }
        return ret;
}

/**
 * intel_lvds_init - setup LVDS connectors on this device
 * @dev: drm device
 *
 * Create the connector, register the LVDS DDC bus, and try to figure out what
 * modes we can display on the LVDS panel (if present).
 */
void intel_lvds_init(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_encoder *intel_encoder;
        struct intel_connector *intel_connector;
        struct drm_connector *connector;
        struct drm_encoder *encoder;
        struct drm_display_mode *scan; /* *modes, *bios_mode; */
        struct drm_crtc *crtc;
        struct intel_lvds_priv *lvds_priv;
        u32 lvds;
        int pipe, gpio = GPIOC;

        /* Skip init on machines we know falsely report LVDS */
        if (dmi_check_system(intel_no_lvds))
                return;

        if (!lvds_is_present_in_vbt(dev)) {
                DRM_DEBUG_KMS("LVDS is not present in VBT\n");
                return;
        }

        if (HAS_PCH_SPLIT(dev)) {
                if ((I915_READ(PCH_LVDS) & LVDS_DETECTED) == 0)
                        return;
                if (dev_priv->edp_support) {
                        DRM_DEBUG_KMS("disable LVDS for eDP support\n");
                        return;
                }
                gpio = PCH_GPIOC;
        }

        intel_encoder = kzalloc(sizeof(struct intel_encoder) +
                                sizeof(struct intel_lvds_priv), GFP_KERNEL);
        if (!intel_encoder) {
                return;
        }

        intel_connector = kzalloc(sizeof(struct intel_connector), GFP_KERNEL);
        if (!intel_connector) {
                kfree(intel_encoder);
                return;
        }

        connector = &intel_connector->base;
        encoder = &intel_encoder->enc;
        drm_connector_init(dev, &intel_connector->base, &intel_lvds_connector_funcs,
                           DRM_MODE_CONNECTOR_LVDS);

        drm_encoder_init(dev, &intel_encoder->enc, &intel_lvds_enc_funcs,
                         DRM_MODE_ENCODER_LVDS);

        drm_mode_connector_attach_encoder(&intel_connector->base, &intel_encoder->enc);
        intel_encoder->type = INTEL_OUTPUT_LVDS;

        intel_encoder->clone_mask = (1 << INTEL_LVDS_CLONE_BIT);
        intel_encoder->crtc_mask = (1 << 1);
        if (IS_I965G(dev))
                intel_encoder->crtc_mask |= (1 << 0);
        drm_encoder_helper_add(encoder, &intel_lvds_helper_funcs);
        drm_connector_helper_add(connector, &intel_lvds_connector_helper_funcs);
        connector->display_info.subpixel_order = SubPixelHorizontalRGB;
        connector->interlace_allowed = false;
        connector->doublescan_allowed = false;

        lvds_priv = (struct intel_lvds_priv *)(intel_encoder + 1);
        intel_encoder->dev_priv = lvds_priv;
        /* create the scaling mode property */
        drm_mode_create_scaling_mode_property(dev);
        /*
         * the initial panel fitting mode will be FULL_SCREEN.
         */

        drm_connector_attach_property(&intel_connector->base,
                                      dev->mode_config.scaling_mode_property,
                                      DRM_MODE_SCALE_ASPECT);
        lvds_priv->fitting_mode = DRM_MODE_SCALE_ASPECT;
        /*
         * LVDS discovery:
         * 1) check for EDID on DDC
         * 2) check for VBT data
         * 3) check to see if LVDS is already on
         *    if none of the above, no panel
         * 4) make sure lid is open
         *    if closed, act like it's not there for now
         */

        /* Set up the DDC bus. */
        intel_encoder->ddc_bus = intel_i2c_create(dev, gpio, "LVDSDDC_C");
        if (!intel_encoder->ddc_bus) {
                dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration "
                           "failed.\n");
                goto failed;
        }

        /*
         * Attempt to get the fixed panel mode from DDC.  Assume that the
         * preferred mode is the right one.
         */
        dev_priv->lvds_edid_good = true;

        if (!intel_ddc_get_modes(connector, intel_encoder->ddc_bus))
                dev_priv->lvds_edid_good = false;

        list_for_each_entry(scan, &connector->probed_modes, head) {
                mutex_lock(&dev->mode_config.mutex);
                if (scan->type & DRM_MODE_TYPE_PREFERRED) {
                        dev_priv->panel_fixed_mode =
                                drm_mode_duplicate(dev, scan);
                        mutex_unlock(&dev->mode_config.mutex);
                        intel_find_lvds_downclock(dev, connector);
                        goto out;
                }
                mutex_unlock(&dev->mode_config.mutex);
        }

        /* Failed to get EDID, what about VBT? */
        if (dev_priv->lfp_lvds_vbt_mode) {
                mutex_lock(&dev->mode_config.mutex);
                dev_priv->panel_fixed_mode =
                        drm_mode_duplicate(dev, dev_priv->lfp_lvds_vbt_mode);
                mutex_unlock(&dev->mode_config.mutex);
                if (dev_priv->panel_fixed_mode) {
                        dev_priv->panel_fixed_mode->type |=
                                DRM_MODE_TYPE_PREFERRED;
                        goto out;
                }
        }

        /*
         * If we didn't get EDID, try checking if the panel is already turned
         * on.  If so, assume that whatever is currently programmed is the
         * correct mode.
         */

        /* Ironlake: FIXME if still fail, not try pipe mode now */
        if (HAS_PCH_SPLIT(dev))
                goto failed;

        lvds = I915_READ(LVDS);
        pipe = (lvds & LVDS_PIPEB_SELECT) ? 1 : 0;
        crtc = intel_get_crtc_from_pipe(dev, pipe);

        if (crtc && (lvds & LVDS_PORT_EN)) {
                dev_priv->panel_fixed_mode = intel_crtc_mode_get(dev, crtc);
                if (dev_priv->panel_fixed_mode) {
                        dev_priv->panel_fixed_mode->type |=
                                DRM_MODE_TYPE_PREFERRED;
                        goto out;
                }
        }

        /* If we still don't have a mode after all that, give up. */
        if (!dev_priv->panel_fixed_mode)
                goto failed;

out:
        if (HAS_PCH_SPLIT(dev)) {
                u32 pwm;
                /* make sure PWM is enabled */
                pwm = I915_READ(BLC_PWM_CPU_CTL2);
                pwm |= (PWM_ENABLE | PWM_PIPE_B);
                I915_WRITE(BLC_PWM_CPU_CTL2, pwm);

                pwm = I915_READ(BLC_PWM_PCH_CTL1);
                pwm |= PWM_PCH_ENABLE;
                I915_WRITE(BLC_PWM_PCH_CTL1, pwm);
        }
        dev_priv->lid_notifier.notifier_call = intel_lid_notify;
        if (acpi_lid_notifier_register(&dev_priv->lid_notifier)) {
                DRM_DEBUG_KMS("lid notifier registration failed\n");
                dev_priv->lid_notifier.notifier_call = NULL;
        }
        /* keep the LVDS connector */
        dev_priv->int_lvds_connector = connector;
        drm_sysfs_connector_add(connector);
        return;

failed:
        DRM_DEBUG_KMS("No LVDS modes found, disabling.\n");
        if (intel_encoder->ddc_bus)
                intel_i2c_destroy(intel_encoder->ddc_bus);
        drm_connector_cleanup(connector);
        drm_encoder_cleanup(encoder);
        kfree(intel_encoder);
        kfree(intel_connector);
}