drm/i915: Make intel_crtc->config a pointer

[linux/fpc-iii.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 void i8xx_fbc_disable(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        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 drm_crtc *crtc)
{
        struct drm_device *dev = crtc->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_framebuffer *fb = crtc->primary->fb;
        struct drm_i915_gem_object *obj = intel_fb_obj(fb);
        struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
        int cfb_pitch;
        int i;
        u32 fbc_ctl;

        dev_priv->fbc.enabled = true;

        cfb_pitch = dev_priv->fbc.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))
                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 * 4), 0);

        if (IS_GEN4(dev)) {
                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(intel_crtc->plane);
                I915_WRITE(FBC_CONTROL2, fbc_ctl2);
                I915_WRITE(FBC_FENCE_OFF, crtc->y);
        }

        /* 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))
                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->y, plane_name(intel_crtc->plane));
}

static bool i8xx_fbc_enabled(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;

        return I915_READ(FBC_CONTROL) & FBC_CTL_EN;
}

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

        dev_priv->fbc.enabled = true;

        dpfc_ctl = DPFC_CTL_PLANE(intel_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, crtc->y);

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

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

static void g4x_fbc_disable(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        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_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;

        return I915_READ(DPFC_CONTROL) & DPFC_CTL_EN;
}

static void snb_fbc_blit_update(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 blt_ecoskpd;

        /* Make sure blitter notifies FBC of writes */

        /* Blitter is part of Media powerwell on VLV. No impact of
         * his param in other platforms for now */
        gen6_gt_force_wake_get(dev_priv, FORCEWAKE_MEDIA);

        blt_ecoskpd = I915_READ(GEN6_BLITTER_ECOSKPD);
        blt_ecoskpd |= GEN6_BLITTER_FBC_NOTIFY <<
                GEN6_BLITTER_LOCK_SHIFT;
        I915_WRITE(GEN6_BLITTER_ECOSKPD, blt_ecoskpd);
        blt_ecoskpd |= GEN6_BLITTER_FBC_NOTIFY;
        I915_WRITE(GEN6_BLITTER_ECOSKPD, blt_ecoskpd);
        blt_ecoskpd &= ~(GEN6_BLITTER_FBC_NOTIFY <<
                         GEN6_BLITTER_LOCK_SHIFT);
        I915_WRITE(GEN6_BLITTER_ECOSKPD, blt_ecoskpd);
        POSTING_READ(GEN6_BLITTER_ECOSKPD);

        gen6_gt_force_wake_put(dev_priv, FORCEWAKE_MEDIA);
}

static void ilk_fbc_enable(struct drm_crtc *crtc)
{
        struct drm_device *dev = crtc->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_framebuffer *fb = crtc->primary->fb;
        struct drm_i915_gem_object *obj = intel_fb_obj(fb);
        struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
        u32 dpfc_ctl;

        dev_priv->fbc.enabled = true;

        dpfc_ctl = DPFC_CTL_PLANE(intel_crtc->plane);
        if (drm_format_plane_cpp(fb->pixel_format, 0) == 2)
                dev_priv->fbc.threshold++;

        switch (dev_priv->fbc.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))
                dpfc_ctl |= obj->fence_reg;

        I915_WRITE(ILK_DPFC_FENCE_YOFF, crtc->y);
        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)) {
                I915_WRITE(SNB_DPFC_CTL_SA,
                           SNB_CPU_FENCE_ENABLE | obj->fence_reg);
                I915_WRITE(DPFC_CPU_FENCE_OFFSET, crtc->y);
                snb_fbc_blit_update(dev);
        }

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

static void ilk_fbc_disable(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        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_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;

        return I915_READ(ILK_DPFC_CONTROL) & DPFC_CTL_EN;
}

static void gen7_fbc_enable(struct drm_crtc *crtc)
{
        struct drm_device *dev = crtc->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_framebuffer *fb = crtc->primary->fb;
        struct drm_i915_gem_object *obj = intel_fb_obj(fb);
        struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
        u32 dpfc_ctl;

        dev_priv->fbc.enabled = true;

        dpfc_ctl = IVB_DPFC_CTL_PLANE(intel_crtc->plane);
        if (drm_format_plane_cpp(fb->pixel_format, 0) == 2)
                dev_priv->fbc.threshold++;

        switch (dev_priv->fbc.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;

        I915_WRITE(ILK_DPFC_CONTROL, dpfc_ctl | DPFC_CTL_EN);

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

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

        snb_fbc_blit_update(dev);

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

/**
 * intel_fbc_enabled - Is FBC enabled?
 * @dev: the drm_device
 *
 * 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_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;

        return dev_priv->fbc.enabled;
}

void bdw_fbc_sw_flush(struct drm_device *dev, u32 value)
{
        struct drm_i915_private *dev_priv = dev->dev_private;

        if (!IS_GEN8(dev))
                return;

        if (!intel_fbc_enabled(dev))
                return;

        I915_WRITE(MSG_FBC_REND_STATE, value);
}

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_device *dev = work->crtc->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        mutex_lock(&dev->struct_mutex);
        if (work == dev_priv->fbc.fbc_work) {
                /* Double check that we haven't switched fb without cancelling
                 * the prior work.
                 */
                if (work->crtc->primary->fb == work->fb) {
                        dev_priv->display.enable_fbc(work->crtc);

                        dev_priv->fbc.plane = to_intel_crtc(work->crtc)->plane;
                        dev_priv->fbc.fb_id = work->crtc->primary->fb->base.id;
                        dev_priv->fbc.y = work->crtc->y;
                }

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

        kfree(work);
}

static void intel_fbc_cancel_work(struct drm_i915_private *dev_priv)
{
        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_enable(struct drm_crtc *crtc)
{
        struct intel_fbc_work *work;
        struct drm_device *dev = crtc->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        if (!dev_priv->display.enable_fbc)
                return;

        intel_fbc_cancel_work(dev_priv);

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

        work->crtc = crtc;
        work->fb = crtc->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));
}

/**
 * intel_fbc_disable - disable FBC
 * @dev: the drm_device
 *
 * This function disables FBC.
 */
void intel_fbc_disable(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;

        intel_fbc_cancel_work(dev_priv);

        if (!dev_priv->display.disable_fbc)
                return;

        dev_priv->display.disable_fbc(dev);
        dev_priv->fbc.plane = -1;
}

static bool set_no_fbc_reason(struct drm_i915_private *dev_priv,
                              enum no_fbc_reason reason)
{
        if (dev_priv->fbc.no_fbc_reason == reason)
                return false;

        dev_priv->fbc.no_fbc_reason = reason;
        return true;
}

/**
 * intel_fbc_update - enable/disable FBC as needed
 * @dev: the drm_device
 *
 * Set up the framebuffer compression hardware at mode set time.  We
 * enable it if possible:
 *   - plane A only (on pre-965)
 *   - no pixel mulitply/line duplication
 *   - no alpha buffer discard
 *   - no dual wide
 *   - framebuffer <= max_hdisplay in width, max_vdisplay in height
 *
 * We can't assume that any compression will take place (worst case),
 * so the compressed buffer has to be the same size as the uncompressed
 * one.  It also must reside (along with the line length buffer) in
 * stolen memory.
 *
 * We need to enable/disable FBC on a global basis.
 */
void intel_fbc_update(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_crtc *crtc = NULL, *tmp_crtc;
        struct intel_crtc *intel_crtc;
        struct drm_framebuffer *fb;
        struct drm_i915_gem_object *obj;
        const struct drm_display_mode *adjusted_mode;
        unsigned int max_width, max_height;

        if (!HAS_FBC(dev)) {
                set_no_fbc_reason(dev_priv, FBC_UNSUPPORTED);
                return;
        }

        if (!i915.powersave) {
                if (set_no_fbc_reason(dev_priv, FBC_MODULE_PARAM))
                        DRM_DEBUG_KMS("fbc disabled per module param\n");
                return;
        }

        /*
         * If FBC is already on, we just have to verify that we can
         * keep it that way...
         * Need to disable if:
         *   - more than one pipe is active
         *   - changing FBC params (stride, fence, mode)
         *   - new fb is too large to fit in compressed buffer
         *   - going to an unsupported config (interlace, pixel multiply, etc.)
         */
        for_each_crtc(dev, tmp_crtc) {
                if (intel_crtc_active(tmp_crtc) &&
                    to_intel_crtc(tmp_crtc)->primary_enabled) {
                        if (crtc) {
                                if (set_no_fbc_reason(dev_priv, FBC_MULTIPLE_PIPES))
                                        DRM_DEBUG_KMS("more than one pipe active, disabling compression\n");
                                goto out_disable;
                        }
                        crtc = tmp_crtc;
                }
        }

        if (!crtc || crtc->primary->fb == NULL) {
                if (set_no_fbc_reason(dev_priv, FBC_NO_OUTPUT))
                        DRM_DEBUG_KMS("no output, disabling\n");
                goto out_disable;
        }

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

        if (i915.enable_fbc < 0) {
                if (set_no_fbc_reason(dev_priv, FBC_CHIP_DEFAULT))
                        DRM_DEBUG_KMS("disabled per chip default\n");
                goto out_disable;
        }
        if (!i915.enable_fbc) {
                if (set_no_fbc_reason(dev_priv, FBC_MODULE_PARAM))
                        DRM_DEBUG_KMS("fbc disabled per module param\n");
                goto out_disable;
        }
        if ((adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE) ||
            (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)) {
                if (set_no_fbc_reason(dev_priv, FBC_UNSUPPORTED_MODE))
                        DRM_DEBUG_KMS("mode incompatible with compression, "
                                      "disabling\n");
                goto out_disable;
        }

        if (INTEL_INFO(dev)->gen >= 8 || IS_HASWELL(dev)) {
                max_width = 4096;
                max_height = 4096;
        } else if (IS_G4X(dev) || INTEL_INFO(dev)->gen >= 5) {
                max_width = 4096;
                max_height = 2048;
        } else {
                max_width = 2048;
                max_height = 1536;
        }
        if (intel_crtc->config->pipe_src_w > max_width ||
            intel_crtc->config->pipe_src_h > max_height) {
                if (set_no_fbc_reason(dev_priv, FBC_MODE_TOO_LARGE))
                        DRM_DEBUG_KMS("mode too large for compression, disabling\n");
                goto out_disable;
        }
        if ((INTEL_INFO(dev)->gen < 4 || HAS_DDI(dev)) &&
            intel_crtc->plane != PLANE_A) {
                if (set_no_fbc_reason(dev_priv, FBC_BAD_PLANE))
                        DRM_DEBUG_KMS("plane not A, disabling compression\n");
                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) {
                if (set_no_fbc_reason(dev_priv, FBC_NOT_TILED))
                        DRM_DEBUG_KMS("framebuffer not tiled or fenced, disabling compression\n");
                goto out_disable;
        }
        if (INTEL_INFO(dev)->gen <= 4 && !IS_G4X(dev) &&
            to_intel_plane(crtc->primary)->rotation != BIT(DRM_ROTATE_0)) {
                if (set_no_fbc_reason(dev_priv, FBC_UNSUPPORTED_MODE))
                        DRM_DEBUG_KMS("Rotation unsupported, disabling\n");
                goto out_disable;
        }

        /* If the kernel debugger is active, always disable compression */
        if (in_dbg_master())
                goto out_disable;

        if (i915_gem_stolen_setup_compression(dev, obj->base.size,
                                              drm_format_plane_cpp(fb->pixel_format, 0))) {
                if (set_no_fbc_reason(dev_priv, FBC_STOLEN_TOO_SMALL))
                        DRM_DEBUG_KMS("framebuffer too large, disabling compression\n");
                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.plane == intel_crtc->plane &&
            dev_priv->fbc.fb_id == fb->base.id &&
            dev_priv->fbc.y == crtc->y)
                return;

        if (intel_fbc_enabled(dev)) {
                /* 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);
        }

        intel_fbc_enable(crtc);
        dev_priv->fbc.no_fbc_reason = FBC_OK;
        return;

out_disable:
        /* Multiple disables should be harmless */
        if (intel_fbc_enabled(dev)) {
                DRM_DEBUG_KMS("unsupported config, disabling FBC\n");
                intel_fbc_disable(dev);
        }
        i915_gem_stolen_cleanup_compression(dev);
}

/**
 * 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)
{
        if (!HAS_FBC(dev_priv)) {
                dev_priv->fbc.enabled = false;
                return;
        }

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