[RFC] drm/atomic: Abuse legacy cursor update flag for legacy gamma update too

[Maarten Lankhorst]

Programs like redshift set the legacy gamma for X.org every 5 seconds.
Because atomic commits wait for vblank completion, we get a frame drop
every 5 seconds because of the legacy gamma update.

Work around this by setting the legacy_cursor_update flag, to force
legacy gamma updates not to be synced against vblank.

Reported-by: Tholin #intel-gfx
Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 drivers/gpu/drm/drm_atomic_helper.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index ae3cbfe9e01c..f37ab26ef4d2 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -3806,6 +3806,9 @@ int drm_atomic_helper_legacy_gamma_set(struct drm_crtc *crtc,
 	if (!state)
 		return -ENOMEM;
 
+	/* Don't wait for vblank after updating gamma. */
+	state->legacy_cursor_update = true;
+
 	blob = drm_property_create_blob(dev,
 					sizeof(struct drm_color_lut) * size,
 					NULL);
-- 
2.16.1