[Intel-gfx] [PATCH] drm/i915: Clear intel_crtc->atomic before updating it.

[Maarten Lankhorst]

If an atomic update fails intel_crtc->atomic may have have some values left
from the last atomic check. One example is atomic->wait_for_vblank,
which results in spurious errors in kms_flip.

Testcase: kms_flip
Reported-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: stable at vger.kernel.org #v4.3
Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index b5f7493213b7..b9539b14fe0d 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -13141,6 +13141,9 @@ static int intel_atomic_check(struct drm_device *dev,
 		struct intel_crtc_state *pipe_config =
 			to_intel_crtc_state(crtc_state);
 
+		memset(&to_intel_crtc(crtc)->atomic, 0,
+		       sizeof(struct intel_crtc_atomic_commit));
+
 		/* Catch I915_MODE_FLAG_INHERITED */
 		if (crtc_state->mode.private_flags != crtc->state->mode.private_flags)
 			crtc_state->mode_changed = true;