linux-kernel - Re: [REGRESSION] amdgpu: thinkpad e495 backlight brightness resets after suspend

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Message-ID: <CADnq5_M-aPD6tNppQ3_6dC8dgt7zeLXZPE5CdCjQEuEDxS=mWA@mail.gmail.com>
Date: Mon, 23 Dec 2024 10:08:41 -0500
From: Alex Deucher <alexdeucher@...il.com>
To: Siva Mahadevan <me@...hdvn.name>
Cc: alexander.deucher@....com, regressions@...ts.linux.dev, 
	stable@...r.kernel.org, amd-gfx@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, Xinhui.Pan@....com, christian.koenig@....com
Subject: Re: [REGRESSION] amdgpu: thinkpad e495 backlight brightness resets
 after suspend

On Mon, Dec 23, 2024 at 4:08 AM Siva Mahadevan <me@...hdvn.name> wrote:
>
> #regzbot introduced: 99a02eab8
>
> Observed behaviour:
> linux-stable v6.12.5 has a regression on my thinkpad e495 where
> suspend/resume of the laptop results in my backlight brightness settings
> to be reset to some very high value. After resume, I'm able to increase
> brightness further until max brightness, but I'm not able to decrease it
> anymore.
>
> Behaviour prior to regression:
> linux-stable v6.12.4 correctly maintains the same brightness setting on
> the backlight that was set prior to suspend/resume.
>
> Notes:
> I bisected this issue between v6.12.4 and v6.12.5 to commit 99a02eab8
> titled "drm/amdgpu: rework resume handling for display (v2)".

Odd.  That commit shouldn't affect the backlight per se.

>
> Hardware:
> * lenovo thinkpad e495
> * AMD Ryzen 5 3500U with Radeon Vega Mobile Gfx
> * VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI]
>   Picasso/Raven 2 [Radeon Vega Series / Radeon Vega Mobile Series]
>   (rev c2)

Please file a ticket here:
https://gitlab.freedesktop.org/drm/amd/-/issues
and attach your full dmesg output and we'll take a look.

Thanks,

Alex