[PATCH 4.20 049/352] drm/amd/display: fix gamma not being applied correctly

[Greg Kroah-Hartman]

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 8ce504b9389be846bcdf512ed5be8f661b3bf097 ]

[why]
Gamma was always being set as identity on SDR monitor,
leading to no changes in gamma. This caused nightlight to
not apply correctly.

[how]
Added a default gamma structure to compare against
in the sdr case.

Signed-off-by: Murton Liu <murton.liu@xxxxxxx>
Reviewed-by: Krunoslav Kovac <Krunoslav.Kovac@xxxxxxx>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
index 193184affefb..32e4c653b1b4 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
@@ -1226,7 +1226,8 @@ static bool dcn10_set_input_transfer_func(struct pipe_ctx *pipe_ctx,
 		tf = plane_state->in_transfer_func;
 
 	if (plane_state->gamma_correction &&
-		!plane_state->gamma_correction->is_identity
+		!dpp_base->ctx->dc->debug.always_use_regamma
+		&& !plane_state->gamma_correction->is_identity
 			&& dce_use_lut(plane_state->format))
 		dpp_base->funcs->dpp_program_input_lut(dpp_base, plane_state->gamma_correction);
 
-- 
2.19.1