Display brightness set to 100% after reboot

English Install/Boot/Login
1

Hi, lately I have noticed my Samsung screen is set to 100% brightness after each reboot. There are no settings in my ASUS Bios for this, and it seems after the OS is started. I believe this started after some OS updates during last week or two, hard to say excactly.

Operating System: openSUSE Tumbleweed 20241010
KDE Plasma Version: 6.2.0
KDE Frameworks Version: 6.6.0
Qt Version: 6.7.3
Kernel Version: 6.11.2-1-default (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 7600 6-Core Processor
Memory: 30.6 GiB of RAM
Graphics Processor: AMD Radeon Graphics
Manufacturer: ASUS

(The GPU is integrated in the CPU, no additional card).

Thanks.

2

Is this a laptop? Is this the laptop display? Did you try to set the brightness via the tray icon for brightness and color control?

3

Hi, no this is a stationary PC. After reboot, it actually changes the brightnes setting in the physical display itself. If I turn off / on the display, my preferred setting remains.

4

Are you doing any colour-management? In a Plasma-Wayland session, this happens in the ‘Display & Monitor’ section of the System Settings app, as opposed to the ‘Colour Management’ section in a Plasma-X11 session (which doesn’t even exist unless ‘colord-kde’ is installed).

When I boot my system, sddm is it’s native, higher brightness, then it returns to my colour-managed lower setting once I log in - I believe this is because the login screen has no means of telling Wayland (or colord in X11) which profile to use.

5

See KDE Discuss powerdevil-is-re-setting-my-display-brightness-after-the-display-wakes-up

1 Like
6

Interesting link on powerdevil.

I checked on my desktop system:

> systemctl --user status plasma-powerdevil.service
● plasma-powerdevil.service - Powerdevil
     Loaded: loaded (/usr/lib/systemd/user/plasma-powerdevil.service; static)
     Active: active (running) since Sun 2024-10-13 08:28:41 CEST; 17min ago
<cut>

org_kde_powerdevil[2201]: Initializing libddcutil.  ddcutil version: 2.1.4, shared library: /usr/lib64/libddcutil.so.5.1.2
org_kde_powerdevil[2201]: Options passed from client:
org_kde_powerdevil[2201]: Applying combined options:
org_kde_powerdevil[2201]: Library initialization complete.
org_kde_powerdevil[2201]: org.kde.powerdevil: [DDCutilDetector]: Failed to initialize callback
org_kde_powerdevil[2201]: org.kde.powerdevil: org.kde.powerdevil.chargethresholdhelper.getthreshold failed "Charge thresholds are not supported by the kernel for this hardware"
org_kde_powerdevil[2201]: org.kde.powerdevil: org.kde.powerdevil.backlighthelper.brightness failed
systemd[1870]: Started Powerdevil.

I do not have this problem, I think I understand why.

7

mchnz…

Thanks for the info, at least I know there might be some issue about it.
Not a big problem, and if it will be solved some time, I can live with it for a while.

8

Further testing…in my case brightness is not adjusted after wake-up, only after reboot. After reboot, it is not adjusted at the login screen, but after login when my desktop shows up, brightness is set to 100% (checked on the physical display by pushing its physical button and entering its menu ). This happens each reboot and seems consistent.

9

I have experienced the brightness issue after wake up from resume (not reboot) with the update to kernel 6.11 (AMD Ryzen 7 PRO, KDE with Xorg/Wayland), versions 6.10.x work just fine. In fact, with kernel 6.11 several patches on amdgpu panel power savings have been introduced (cf. the comment of AMD dev Mario Limonciello at https://gitlab.freedesktop.org/upower/power-profiles-daemon/-/issues/159). What does ‘cat /sys/class/drm/card1-eDP-1/amdgpu/panel_power_savings’ show? Does adding amdgpu.abmlevel=0 to the kernel command line solve the issue? By the way, the issue disappeared for me recently, not sure which update solved it.