[Intel-gfx] [PATCH] [VPG HSW-A] drm/i915: Fix for YouTube full screen video playback flicker issue

[Shanth Kumar]

During full screen video playback on Primary Display[eDP],
when the player UI(player controls) is superimposed on video frame,
the Sprite plane is disabled and rendering happens on Primary plane.
And when the player UI fades away, the Primary plane is disabled,
and rendering happens on Sprite plane. This is done for power saving purpose.
While disabling Primary plane or Sprite plane we see a momentary flicker.
This patch waits on a vblank before disabling the Primary or Sprite plane.
Detailed testing was done with this patch to confirm issue is not reproduced.
No performance drop or visible user experience degradation seen with this
change.

HSD ID for this issue is 5180815

Change Details-
drm/i915: intel_wait_for_vblank() is introduced before calling
intel_disable_primary() in function intel_update_plane(intel_sprite.c),
after checking to_intel_crtc(crtc)->primary_disabled flag being false.
drm/i915: intel_wait_for_vblank() is introduced before calling
intel_plane->disable_plane() in function intel_update_plane(intel_sprite.c)

Change-Id: Ief8a250ffc96d961b444c5dd86bcbe219a3a7000
Signed-off-by: vkannan <vandana.kannan at intel.com>
Signed-off-by: Pradeep Bhat <pradeep.bhat at intel.com>
Signed-off-by: Shanth Kumar <shanth.kumarx.shivalingappa at intel.com>
---
 drivers/gpu/drm/i915/intel_sprite.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index 1fa5612..470008a 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -824,8 +824,10 @@ intel_update_plane(struct drm_plane *plane, struct drm_crtc *crtc,
 	else
 		intel_plane->disable_plane(plane);
 
-	if (disable_primary)
+	if (disable_primary && !(to_intel_crtc(crtc)->primary_disabled)) {
+		intel_wait_for_vblank(dev, to_intel_crtc(crtc)->pipe);
 		intel_disable_primary(crtc);
+	}
 
 	/* Unpin old obj after new one is active to avoid ugliness */
 	if (old_obj) {
@@ -857,13 +859,13 @@ intel_disable_plane(struct drm_plane *plane)
 
 	if (plane->crtc)
 		intel_enable_primary(plane->crtc);
+
+	intel_wait_for_vblank(dev, intel_plane->pipe);
 	intel_plane->disable_plane(plane);
 
 	if (!intel_plane->obj)
 		goto out;
 
-	intel_wait_for_vblank(dev, intel_plane->pipe);
-
 	mutex_lock(&dev->struct_mutex);
 	intel_unpin_fb_obj(intel_plane->obj);
 	intel_plane->obj = NULL;
-- 
1.7.9.5