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[regression][bisected] Screen backlight is turned off when I press the Brightness Down key

Brief summary of the problem:

After a suspend and resume, screen backlight is turned off when I press the Brightness Down key. I can only see the content on screen with a flashlight.

It's a Lenovo Ideapad S540-13ARE laptop.

Hardware description:

  • CPU: AMD Ryzen 7 4800U with Radeon Graphics
  • GPU: integrated
  • System Memory: 16 GB
  • Display(s): laptop display
  • Type of Diplay Connection: eDP

System infomration:

  • Distro name and Version: Arch Linux latest
  • Kernel version: 5.11.4
  • Custom kernel: N/A
  • AMD package version: No package

How to reproduce the issue:

  • Boot and login to TTY.
  • Suspend with sudo systemctl suspend.
  • Resume.
  • Press the Brightness Down key.
  • Result: Screen backlight is off.

(Similar behavior is also found in KDE.)

Bisecting

Bisecting between 5.10 to 5.11 gives me this:

5fe6b98ae00dc2e0ac24ef8a45d828b82a4aae90 is the first bad commit
commit 5fe6b98ae00dc2e0ac24ef8a45d828b82a4aae90
Author: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Date:   Fri Nov 13 15:04:54 2020 -0500

    drm/amd/display: Update dmub code
    
    There is a delta in the dmub code
    - add boot options
    - add boot status
    - remove unused auto_load_is_done func pointer
    
    Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
    Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

 drivers/gpu/drm/amd/display/dmub/dmub_srv.h       | 20 ++++++++++++++++-
 drivers/gpu/drm/amd/display/dmub/inc/dmub_cmd.h   |  3 ++-
 drivers/gpu/drm/amd/display/dmub/src/dmub_dcn20.c | 23 ++++++++++++++++++++
 drivers/gpu/drm/amd/display/dmub/src/dmub_dcn20.h |  6 ++++++
 drivers/gpu/drm/amd/display/dmub/src/dmub_dcn21.c |  5 -----
 drivers/gpu/drm/amd/display/dmub/src/dmub_dcn21.h |  2 --
 drivers/gpu/drm/amd/display/dmub/src/dmub_dcn30.c |  5 -----
 drivers/gpu/drm/amd/display/dmub/src/dmub_dcn30.h |  1 -
 drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c   | 26 +++++++++++++++++------
 9 files changed, 70 insertions(+), 21 deletions(-)

Reverting 5fe6b98ae00dc2e0ac24ef8a45d828b82a4aae90 on 5.11.4 branch fixes the issue for me.

Attached files:

No useful logs found.

With drm log level 0xFF (echo 0xFF > /sys/module/drm/parameters/debug), I only see this:

[drm:amdgpu_acpi_event [amdgpu]] event, device_class = video, type = 0x87
Edited by Rvfg