Re: [PATCH] drm/amd/display: Avoid using zero AC/DC brightness levels

[Mario Limonciello <mario.limonciello@amd.com>]

On 5/29/26 14:13, edson drosdeck wrote:
> Hi,
> 
> Please find attached the requested ACPI dump and EDID files:
> 
> acpidump.txt
> edid.txt
> 
> Thanks for taking a look.

Sorry for my delay.  I looked through your acpidump and you don't have 
an ATIF method (which would indicate preferred brightness values for AC 
and DC).

I had expected this case is handled by 
amdgpu_dm_update_backlight_caps(), but it appears that only sets min/max 
not ac/dc default levels.

Can you see if this helps?

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 832223c06b3f5..e2831bf48eaab 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -5213,6 +5213,8 @@ static void amdgpu_dm_update_backlight_caps(struct 
amdgpu_display_manager *dm,
         if (!caps->caps_valid) {
                 caps->min_input_signal = AMDGPU_DM_DEFAULT_MIN_BACKLIGHT;
                 caps->max_input_signal = AMDGPU_DM_DEFAULT_MAX_BACKLIGHT;
+               caps->ac_level = 50;
+               caps->dc_level = 50;
                 caps->caps_valid = true;
         }
  #else