"Issue: Display brightness is locked at a low level after waking from sleep on CachyOS (latest update)

General
1

Hi, After doing latest update of cachyos

Dual-monitor setup. Software brightness controls indicate 100%, but the actual output is significantly dimmer. Workaround: Logging out and restarting the session restores normal brightness levels."

Here you have my spec:

Kernel: Linux 6.19.10-1-cachyos
Display (BOE0CDD): 1920x1200 in 16", 144 Hz
Display (MX279): 1920x1080 in 27", 60 Hz [Exte]
DE: KDE Plasma 6.6.3
WM: KWin (Wayland)
WM Theme: Breeze
Theme: Breeze (Dark) [Qt], Breeze-Dark [GTK2],]
CPU: AMD Ryzen AI 7 350 (16) @ 5.09 GHz
GPU 1: AMD Radeon 860M Graphics [Integrated]
GPU 2: NVIDIA GeForce RTX 5050 Max-Q / Mobile ]
Memory: 19.63 GiB / 30.36 GiB (65%)

Thanks.

2

same here, same here

3

Hey,

Ive been facing this issue too. This seems to be a bug in “powerdevil” in KDE. I did not had time to create a fix for this, since when looking fastly over I do not see an issue in the recent changes of powerdevil.

You can fix it with disabling “dimming” in the power settings. Ill do soon a bug report to KDE, but basically the issue is that the Powerdevil does not restore the dim after waking up. It keeps the screen dimmed.

4

Running this command (partially) fixes it I believe:
kscreen-doctor output.eDP-1.dimming.100
Edit: It’s more of a bandaid fix as setting your brightness to anything else causes the dimming to come back.

A restart also fixes it permanently until it happens again due to dimming before sleep.

5

The bug seems to be tracked in these issues:

https://bugs.kde.org/show_bug.cgi?id=513809
https://bugs.kde.org/show_bug.cgi?id=516631
6

According to those bug tracking, the issue has been resolved. However, as soon as I my CachyOS awakes, brightness is dimmed and I must restart.

I cannot set HDR mode since it switches to 4:2:2 for whatever reason

7

I found that re-connecting the monitor resets brightness level.

8

Until it is really fixed (at the time of writing it still does happen), and does not happen anymore, here is how you can reset your brightness without rebooting:

  • Find the name of your display output: kscreen-doctor -o
  • Use the output, for example, eDP-3 in the command to reset the brightness:
  • kscreen-doctor output.eDP-3.dimming.100