[PATCH 5.4 315/344] radeon: insert 10ms sleep in dce5_crtc_load_lut

From: Greg Kroah-Hartman
Date: Fri Feb 21 2020 - 03:14:59 EST

From: Daniel Vetter <daniel.vetter@xxxxxxxx>

[ Upstream commit ec3d65082d7dabad6fa8f66a8ef166f2d522d6b2 ]

Per at least one tester this is enough magic to recover the regression
introduced for some people (but not all) in

commit b8e2b0199cc377617dc238f5106352c06dcd3fa2
Author: Peter Rosin <peda@xxxxxxxxxx>
Date: Tue Jul 4 12:36:57 2017 +0200

drm/fb-helper: factor out pseudo-palette

which for radeon had the side-effect of refactoring out a seemingly
redudant writing of the color palette.

10ms in a fairly slow modeset path feels like an acceptable form of
duct-tape, so maybe worth a shot and see what sticks.

Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Michel DÃnzer <michel.daenzer@xxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/gpu/drm/radeon/radeon_display.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index e81b01f8db90e..0826efd9b5f51 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -127,6 +127,8 @@ static void dce5_crtc_load_lut(struct drm_crtc *crtc)

DRM_DEBUG_KMS("%d\n", radeon_crtc->crtc_id);

+ msleep(10);
WREG32(NI_INPUT_CSC_CONTROL + radeon_crtc->crtc_offset,