linux-kernel - Re: AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

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Message-ID: <CAMb39_nRz-9NemdsASTG_34Lm_6a1uw4qLwkqBdn7FnMmN3O7w@mail.gmail.com>
Date: Sat, 21 Jun 2025 11:03:11 -0500
From: Walt Holman <waltholman09@...il.com>
To: Mario Limonciello <superm1@...nel.org>
Cc: linux-kernel <linux-kernel@...r.kernel.org>, mario.limonciello@....com, 
	alexander.deucher@....com
Subject: Re: AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

On Sat, Jun 21, 2025 at 10:52 AM Mario Limonciello <superm1@...nel.org> wrote:
>
>
>
> On 6/21/25 10:18 AM, Walt Holman wrote:
> > Hello,
> >
> > With the latest drm fixes this week on 6.16-rc2, I am experiencing a
> > black screen instead of the sddm greeter and the GPU appears to be
> > locked up. I can ssh into the laptop and reboot it, but that's about
> > it. I have bisected the commit to commit id:
> > 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a and upon reverting the
> > commit, the system works as normal. The hardware is an Asus Rog
> > Zephyrus G16 with AMD Ryzen AI 9 HX 370 w/ Radeon 890M video. I'm able
> > to test patches etc.. if need be.
>
> Hi there,
>
> By chance do you have an OLED panel?  If so can you please try the patch
> attached to this bug?
>
> https://gitlab.freedesktop.org/drm/amd/-/issues/4338
>
> Thanks,
>
> >
> > 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a is the first bad commit
> > commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a (HEAD)
> > Author: Mario Limonciello <mario.limonciello@....com>
> > Date:   Thu May 29 09:46:32 2025 -0500
> >
> >      drm/amd/display: Export full brightness range to userspace
> >
> >      [WHY]
> >      Userspace currently is offered a range from 0-0xFF but the PWM is
> >      programmed from 0-0xFFFF.  This can be limiting to some software
> >      that wants to apply greater granularity.
> >
> >      [HOW]
> >      Convert internally to firmware values only when mapping custom
> >      brightness curves because these are in 0-0xFF range. Advertise full
> >      PWM range to userspace.
> >
> >      Cc: Mario Limonciello <mario.limonciello@....com>
> >      Cc: Alex Deucher <alexander.deucher@....com>
> >      Reviewed-by: Roman Li <roman.li@....com>
> >      Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> >      Signed-off-by: Alex Hung <alex.hung@....com>
> >      Tested-by: Daniel Wheeler <daniel.wheeler@....com>
> >      Signed-off-by: Alex Deucher <alexander.deucher@....com>
> >      (cherry picked from commit 8dbd72cb790058ce52279af38a43c2b302fdd3e5)
> >      Cc: stable@...r.kernel.org
> >
> >   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 41
> > +++++++++++++++++++++++++++--------------
> >   1 file changed, 27 insertions(+), 14 deletions(-)
> >
>

Yes, I do have an OLED panel and that patch does make it visible
again. It is still very dark, but visible.

-Walt