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

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

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.limonciello@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
>>
>>