Kernel 6.1.7-1 broken brightness function key combo on latest update

Hi everyone! The latest update broke the function key combo used for modifying the brightness level. All the other function combos work. sudo showkey shows that both the normal and “alternate” keypresses are registered. Following is some relevant system info as returned by inxi -v7azy:

  Kernel: 6.1.7-1-MANJARO arch: x86_64 bits: 64 compiler: gcc v: 12.2.1
    parameters: BOOT_IMAGE=/boot/vmlinuz-6.1-x86_64
    root=UUID=5270a6c4-4091-4dd4-b786-4c8e3ffe0481 ro quiet apparmor=1
    security=apparmor udev.log_priority=3 acpi_backlight=vendor nowatchdog

  Desktop: Xfce v: 4.18.0 tk: Gtk v: 3.24.35 info: xfce4-panel wm: xfwm
    v: 4.18.0 dm: LightDM v: 1.32.0 Distro: Manjaro Linux base: Arch Linux
  Mobo: ASUSTeK model: X513IA v: 1.0 serial: <filter>
    UEFI: American Megatrends v: X513IA.308 date: 10/26/2021
  Device-1: AMD Renoir vendor: ASUSTeK driver: amdgpu v: kernel arch: GCN-5.1
    code: Vega-2 process: TSMC n7 (7nm) built: 2018-21 pcie: gen: 4
  Monitor-1: eDP-1 mapped: eDP model: ChiMei InnoLux 0x15e7 built: 2016
    res: 1920x1080 hz: 60 dpi: 142 gamma: 1.2 size: 344x193mm (13.54x7.6")
    diag: 394mm (15.5") ratio: 16:9 modes: max: 1920x1080 min: 640x480

What could be the cause?

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Maybe you need to change that. More investigation you can do by going trough Backlight - ArchWiki


Just out of curiosity, but why exclude that module? Was it manual?

Kernel 61 has reached EOL (right?), so might as well try other kernels, mainly LTS.

No! Is the linux60 6.0.19 that is EOL.

Some systems need the watchdog hardware to be disabled.

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Thank you for pointing me in the right direction! I changed acpi_backlight to native and presto, it worked :partying_face:

Two interesting tidbits:

  • with the previous config /sys/class/backlight/ was empty whereas now it’s the appropriate value (amdgpu_bl0 in my case)
  • the systemd backlight services were missing whereas they’re present and operating correctly now

Out of curiosity, what could’ve been the issue? The only relevant information I could find was the one referenced in the update announcement about 6.1 possibly breaking backlight control on some laptops.


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