[Intel-gfx] [PATCH] drm/i915/display: Add an extra vblank wait before fbc activation

[Uma Shankar]

Add an extra vblank before fbc is activated.
WA: 1409689360
Corruption with FBC around plane 1A enabling. In the Frame Buffer
Compression programming sequence "Display Plane Enabling with FBC"
add a wait for vblank between plane enabling step 1 and FBC enabling
step 2.

Signed-off-by: Uma Shankar <uma.shankar at intel.com>
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
---
 drivers/gpu/drm/i915/display/intel_fbc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
index 2ab32e6532ff..0ed252ff2c53 100644
--- a/drivers/gpu/drm/i915/display/intel_fbc.c
+++ b/drivers/gpu/drm/i915/display/intel_fbc.c
@@ -1085,10 +1085,12 @@ static void __intel_fbc_post_update(struct intel_crtc *crtc)
 	if (!intel_fbc_can_activate(crtc))
 		return;
 
-	if (!fbc->busy_bits)
+	if (!fbc->busy_bits) {
+		intel_wait_for_vblank(dev_priv, crtc->pipe);
 		intel_fbc_hw_activate(dev_priv);
-	else
+	} else {
 		intel_fbc_deactivate(dev_priv, "frontbuffer write");
+	}
 }
 
 void intel_fbc_post_update(struct intel_atomic_state *state,
-- 
2.22.0