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The display brightness adjustment while using Ubuntu on my Thinkpad T14s (AMD CPU + iGPU) does not work.

Specifically, the brightness slider in the settings does not change the brightness of the screen, and the brightness keys similarly does nothing (a popup with the brightness symbol and the currently level appears, though this does not change the actual screen brightness).

What I've tried so far:

Editing the GRUB_CMDLINE_LINUX_DEFAULT line in /etc/default/grub to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor acpi_osi=linux" (as outl2ined in this answer)

Editing the GRUB_CMDLINE_LINUX_DEFAULT line in /etc/default/grub to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force acpi_backlight=native" (as outlined in this answer)

Updating all the drivers through:

sudo apt update
sudo apt upgrade
sudo ubuntu-drivers autoinstall

and updating using the Software Updater app

I've also tried writing to the brightness file with: echo 5 | sudo tee /sys/class/backlight/acpi_video0/brightness

Output of sudo lshw -c video:

  *-display UNCLAIMED       
       description: VGA compatible controller
       product: Advanced Micro Devices, Inc. [AMD/ATI]
       vendor: Advanced Micro Devices, Inc. [AMD/ATI]
       physical id: 0
       bus info: pci@0000:c3:00.0
       version: dd
       width: 64 bits
       clock: 33MHz
       capabilities: pm pciexpress msi msix vga_controller bus_master cap_list
       configuration: latency=0
       resources: iomemory:2c0-2bf memory:2c00000000-2c0fffffff memory:90000000-901fffff ioport:1000(size=256) memory:90500000-9057ffff

Output of xrandr:

xrandr: Failed to get size of gamma for output default
Screen 0: minimum 1920 x 1200, current 1920 x 1200, maximum 1920 x 1200
default connected primary 1920x1200+0+0 0mm x 0mm
   1920x1200     77.00*
KetZoomer
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1 Answers1

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I had a similar issue (could not adjust screen brightness T14s with AMD CPU + iGPU, although Ubuntu 22.04), and I hope that the following helps you. For me the fix was to install the AMD GPU drivers from the AMD-Page. I think that ubuntu-drivers autoinstall might not be enough.

So in more detail:

  1. I downloaded the drivers from here
  2. I installed the drivers through the command: amdgpu-install (docs)
  3. I rebooted and it worked :)

Hope this helps, Thinklex

Thinklex
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