linux-kernel - Re: [PATCH v1 5/5] drm: panel-backlight-quirks: Add Steam Decks

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Message-ID: <0e1e33a6-70a0-40a0-86d9-b8f636b19455@amd.com>
Date: Mon, 25 Aug 2025 16:05:34 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: Antheas Kapenekakis <lkml@...heas.dev>
Cc: amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, philm@...jaro.org,
 Alex Deucher <alexander.deucher@....com>,
 Christian König <christian.koenig@....com>
Subject: Re: [PATCH v1 5/5] drm: panel-backlight-quirks: Add Steam Decks

On 8/25/2025 4:02 PM, Antheas Kapenekakis wrote:
> On Mon, 25 Aug 2025 at 18:47, Mario Limonciello
> <mario.limonciello@....com> wrote:
>>
>> On 8/24/2025 3:02 PM, Antheas Kapenekakis wrote:
>>> On the SteamOS kernel, Valve universally makes minimum brightness 0
>>> for all devices. SteamOS is (was?) meant for the Steam Deck, so
>>> enabling it universally is reasonable. However, it causes issues in
>>> certain devices. Therefore, introduce it just for the Steam Deck here.
>>>
>>> SteamOS kernel does not have a public mirror, but this replaces commit
>>> 806dd74bb225 ("amd/drm: override backlight min value from 12 -> 0")
>>> in the latest, as of this writing, SteamOS kernel (6.11.11-valve24).
>>> See unofficial mirror reconstructed from sources below.
>>>
>>> Link: https://gitlab.com/evlaV/linux-integration/-/commit/806dd74bb225
>>> Signed-off-by: Antheas Kapenekakis <lkml@...heas.dev>
>>> ---
>>
>> Directionally I agree with this commit in favor of what the downstream
>> kernel tree has that you linked above.
>>
>> But I would rather see it sent alone and not tied to a series to
>> overhaul how quirks work.  If it's sent alone we should be able to get
>> it reviewed pretty easily and in drm-misc-fixes.
> 
> That's a good idea. However, this commit relies on patch 1 and 3, as
> it has no edid information and uses a second match.

The EDID half should be a solvable problem.  IE the EDIDs for Steam Deck 
and Steam Deck OLED are known quantities, or a least trivial to dump.

And once you have the EDID in place I'm not sure if you need a second 
match anymore or not really (at least for SD/SD OLED).

> 
> Antheas
> 
>>>    drivers/gpu/drm/drm_panel_backlight_quirks.c | 17 ++++++++++++++++-
>>>    1 file changed, 16 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/drm_panel_backlight_quirks.c b/drivers/gpu/drm/drm_panel_backlight_quirks.c
>>> index 78c430b07d6a..5c24f4a86519 100644
>>> --- a/drivers/gpu/drm/drm_panel_backlight_quirks.c
>>> +++ b/drivers/gpu/drm/drm_panel_backlight_quirks.c
>>> @@ -73,7 +73,22 @@ static const struct drm_get_panel_backlight_quirk drm_panel_min_backlight_quirks
>>>                .dmi_match_other.field = DMI_PRODUCT_NAME,
>>>                .dmi_match_other.value = "ONEXPLAYER F1 EVA-02",
>>>                .quirk = { .brightness_mask = 3, },
>>> -     }
>>> +     },
>>> +     /* Steam Deck models */
>>> +     {
>>> +             .dmi_match.field = DMI_SYS_VENDOR,
>>> +             .dmi_match.value = "Valve",
>>> +             .dmi_match_other.field = DMI_PRODUCT_NAME,
>>> +             .dmi_match_other.value = "Jupiter",
>>> +             .quirk = { .min_brightness = 1, },
>>> +     },
>>> +     {
>>> +             .dmi_match.field = DMI_SYS_VENDOR,
>>> +             .dmi_match.value = "Valve",
>>> +             .dmi_match_other.field = DMI_PRODUCT_NAME,
>>> +             .dmi_match_other.value = "Galileo",
>>> +             .quirk = { .min_brightness = 1, },
>>> +     },
>>>    };
>>>
>>>    static bool drm_panel_min_backlight_quirk_matches(
>>
>>
>