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

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Message-ID: <CAMb39_mAWfeuyDjHR4Ej9fH=PXdH0qUda50R=iqGKVzN1mcHPQ@mail.gmail.com>
Date: Sat, 21 Jun 2025 10:18:42 -0500
From: Walt Holman <waltholman09@...il.com>
To: linux-kernel <linux-kernel@...r.kernel.org>
Cc: mario.limonciello@....com, alexander.deucher@....com
Subject: AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

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.

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(-)