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

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Message-Id: <4YRLYT4ft9z1QXM@panix3.panix.com>
Date: Mon, 06 Jan 2025 04:19:41 +0000
From: Pierre Asselin <pa@...ix.com>
To: me@...hdvn.name, alexdeucher@...il.com
Cc: Xinhui.Pan@....com, stable@...r.kernel.org,
 regressions@...ts.linux.dev, linux-kernel@...r.kernel.org,
 christian.koenig@....com, amd-gfx@...ts.freedesktop.org,
 alexander.deucher@....com
Subject: Re: [REGRESSION] amdgpu: thinkpad e495 backlight brightness resets
 after suspend

Alex Deucher <alexdeucher@...il.com> wrote:

> 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