[PATCH 4.17 182/336] drm/amd/display: Fix dim display on DCE11

[Greg Kroah-Hartman]

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

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

From: "Leo (Sunpeng) Li" <sunpeng.li@xxxxxxx>

[ Upstream commit 84ffa80123f56f80145dc638f21dfcbedda5610d ]

Before programming the input gamma, check that we're not using the
identity correction.

Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@xxxxxxx>
Reviewed-by: Anthony Koo <Anthony.Koo@xxxxxxx>
Acked-by: Harry Wentland <harry.wentland@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
@@ -279,7 +279,9 @@ dce110_set_input_transfer_func(struct pi
 	build_prescale_params(&prescale_params, plane_state);
 	ipp->funcs->ipp_program_prescale(ipp, &prescale_params);
 
-	if (plane_state->gamma_correction && dce_use_lut(plane_state->format))
+	if (plane_state->gamma_correction &&
+			!plane_state->gamma_correction->is_identity &&
+			dce_use_lut(plane_state->format))
 		ipp->funcs->ipp_program_input_lut(ipp, plane_state->gamma_correction);
 
 	if (tf == NULL) {