[PATCH] drm/amd/display: use linear backlight curve on Linux

[Aarav Kumar]

The power module currently uses a non-linear backlight curve for the
Linux backlight path. This results in incorrect brightness levels on
affected systems.

Use the linear backlight curve instead to preserve the existing
brightness-to-PWM mapping.

Tested on an AMD laptop with an eDP panel. The regression was
reproduced with commit 3c108046e1d6 ("drm/amd/display: Add power
module on Linux"), and the brightness behavior was restored with this
change.

Fixes: 3c108046e1d6 ("drm/amd/display: Add power module on Linux")
Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/5723
Signed-off-by: Aarav Kumar <aarav.240604@xxxxxxxxx>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 8d690468d..cd10a5d45 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1913,7 +1913,7 @@ static int amdgpu_dm_init_power_module(struct amdgpu_display_manager *dm)
 			!(amdgpu_dc_feature_mask & DC_DISABLE_FRACTIONAL_PWM_MASK);
 		init_data[i].use_custom_backlight_caps = false;
 		init_data[i].custom_backlight_caps_config_no = 0;
-		init_data[i].use_linear_backlight_curve = false;
+		init_data[i].use_linear_backlight_curve = true;
 		init_data[i].def_varibright_enable = 0;
 		init_data[i].varibright_level = 0;
 		/*
-- 
2.55.0