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

[Mario Limonciello]

On 6/8/26 13:25, edson drosdeck wrote:
Thanks for looking into this.

I tested the proposed change and it fixes the issue on my system. With
this patch applied,
the initial brightness level is set correctly during boot instead of
starting at the minimum level.

Thanks for confirming.  We'll include something like this in a future 
promotion.



Em qua., 3 de jun. de 2026 às 16:23, Mario Limonciello
<mario.limoncie...@amd.com> escreveu:



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