[Intel-gfx] [PATCH] drm/i915: Make wait-for-pending-flips more defensive

[Chris Wilson]

Be sure to always flush a stuck pageflip even if we couldn't possibly
expect one to be there.

References: https://bugs.freedesktop.org/show_bug.cgi?id=82612
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_display.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index a7582a46e82e..5898e7157c4c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3359,11 +3359,7 @@ void intel_crtc_wait_for_pending_flips(struct drm_crtc *crtc)
 	struct drm_device *dev = crtc->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	if (crtc->primary->fb == NULL)
-		return;
-
 	WARN_ON(waitqueue_active(&dev_priv->pending_flip_queue));
-
 	if (WARN_ON(wait_event_timeout(dev_priv->pending_flip_queue,
 				       !intel_crtc_has_pending_flip(crtc),
 				       60*HZ) == 0)) {
@@ -3378,9 +3374,11 @@ void intel_crtc_wait_for_pending_flips(struct drm_crtc *crtc)
 		spin_unlock_irqrestore(&dev->event_lock, flags);
 	}
 
-	mutex_lock(&dev->struct_mutex);
-	intel_finish_fb(crtc->primary->fb);
-	mutex_unlock(&dev->struct_mutex);
+	if (crtc->primary->fb) {
+		mutex_lock(&dev->struct_mutex);
+		intel_finish_fb(crtc->primary->fb);
+		mutex_unlock(&dev->struct_mutex);
+	}
 }
 
 /* Program iCLKIP clock to the desired frequency */
-- 
2.1.0.rc1