drm/i915: Don't clobber crtc->fb when queue_flip fails

commit 4a35f83b2b7c6aae3fc0d1c4554fdc99dc33ad07 upstream.

Restore crtc->fb to the old framebuffer if queue_flip fails.

While at it, kill the pointless intel_fb temp variable.

v2: Update crtc->fb before queue_flip and restore it back
    after a failure.

Backported for 3.8-stable. Restored an atomic_sub removed
in 3.9 ca9c46.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reported-and-Tested-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Lingzhu Xiang <lxiang@redhat.com>
Reviewed-by: CAI Qian <caiqian@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 80aa1fc12f4390ccf68d0bf42ff56fc25056e2d8..e6e4df7cb2926590157aecd8eb1fea7a98b58c41 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7420,8 +7420,8 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 {
        struct drm_device *dev = crtc->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
-       struct intel_framebuffer *intel_fb;
-       struct drm_i915_gem_object *obj;
+       struct drm_framebuffer *old_fb = crtc->fb;
+       struct drm_i915_gem_object *obj = to_intel_framebuffer(fb)->obj;
        struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
        struct intel_unpin_work *work;
        unsigned long flags;
@@ -7446,8 +7446,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 
        work->event = event;
        work->crtc = crtc;
-       intel_fb = to_intel_framebuffer(crtc->fb);
-       work->old_fb_obj = intel_fb->obj;
+       work->old_fb_obj = to_intel_framebuffer(old_fb)->obj;
        INIT_WORK(&work->work, intel_unpin_work_fn);
 
        ret = drm_vblank_get(dev, intel_crtc->pipe);
@@ -7467,9 +7466,6 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
        intel_crtc->unpin_work = work;
        spin_unlock_irqrestore(&dev->event_lock, flags);
 
-       intel_fb = to_intel_framebuffer(fb);
-       obj = intel_fb->obj;
-
        if (atomic_read(&intel_crtc->unpin_work_count) >= 2)
                flush_workqueue(dev_priv->wq);
 
@@ -7507,6 +7503,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 
 cleanup_pending:
        atomic_dec(&intel_crtc->unpin_work_count);
+       crtc->fb = old_fb;
        atomic_sub(1 << intel_crtc->plane, &work->old_fb_obj->pending_flip);
        drm_gem_object_unreference(&work->old_fb_obj->base);
        drm_gem_object_unreference(&obj->base);