SUMMARY The software brightness is reduced when my OLED Monitor comes out of a Pixel-Refresh or is reconnected. This is an issue for OLED Monitors that automatically do Pixel Refresh and other Monitors that get regularly reconnected. STEPS TO REPRODUCE 0. Set brightness to 100% 1. Unplug display cable 2. Reconnect display cable 3. Observe changed brightness OBSERVED RESULT Brightness changes unexpectedly EXPECTED RESULT Preferably brightness stays the same or alternatively brightness is set to full 100%. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Arch Linux KDE Plasma Version: 6.1.4 KDE Frameworks Version: 6.4.0 Qt Version: 6.7.2
Moved to KWin which is responsible for storing and applying software brightness.
Idk if can help, but on my old screens of my pc if I log out KDE try to lower the brightness and never restore the 100% brightness
Please attach ~/.config/kwinoutputconfig.json with the brightness at a 100%, and then again after triggering the issue
Created attachment 173348 [details] kwinoutput and UI in original 100% brightness and after reconnecting the display cable kwinoutput and UI in original 100% brightness and after reconnecting the display cable
The kwinoutputconfig.json file shows no difference after reconnecting. The actual screen brightness stays the same, but the UI brightness got set from 100% to 1% by reconnecting (see attachment AFTER.png in Archiv.tar.gz). After reboot the brightness was back to 100% again, but in other cases it was permanently decreased. I do not know why it did not happen this time.
Created attachment 173349 [details] Manual Pixel Refresh If instead I do a manual pixel refresh with the monitor, I do get the same brightness, but the refresh rate changed from 165 to 100 Hz in kwinoutputconfig.json and the UI.
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Back to REPORTED status as kwinoutputconfig.json before and after have been provided.
I "think" i suffer from the same issue but with the opposite effect. My monitor, when plugged in, goes to full brightness. Also when powered off/on. Debugging should be easy. Grab a laptop, latest KDE/Plasma with Wayland session (this problem doesn't occur under X11) and an external monitor. Put your external monitor as primary (laptop monitor off, external monitor on). Change your monitor brightness on the monitor itself to something that isn't 100%. Turn off the monitor and back on, now it's at 100% again. I'm running 6.2.5 (and took the liberty to update that in this bug too). I'm guessing the cause of this issue is the same as what Lukas reported so the fix probably fixes both issues. I vaguely remember there to be a fix recently where brightness settings were not exclusive to laptops anymore but i can't quite find where i read that. I'll report back when i find it.
(In reply to Mark from comment #9) > Debugging should be easy. Grab a laptop, latest KDE/Plasma with Wayland > session (this problem doesn't occur under X11) and an external monitor. Put > your external monitor as primary (laptop monitor off, external monitor on). > Change your monitor brightness on the monitor itself to something that isn't > 100%. Turn off the monitor and back on, now it's at 100% again. You need to set the brightness in Plasma, not on the monitor. In your case it's bug 494497. In this case though the output config already contains the desired value, but it doesn't get applied somehow.
Ahh, here it is! For reference :) https://blogs.kde.org/2024/09/04/brightness-controls-for-all-your-displays/ Thank you Zamundaaa for the pointer, will reply there instead.