Bug 429580

Summary:	Can't change screen brightness - OSD appears but brightness does not change
Product:	[Plasma] plasmashell	Reporter:	elman <elman>
Component:	general	Assignee:	David Edmundson <kde>
Status:	RESOLVED UPSTREAM
Severity:	normal	CC:	plasma-bugs-null
Priority:	NOR
Version First Reported In:	5.20.3
Target Milestone:	1.0
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description elman 2020-11-24 08:44:11 UTC

SUMMARY
When I try to change brightness via shortcut Fn+F2/F3, OSD appears, but brightness doesn't change. Only 0 % works, which turns display off.

This used to work, but I'm not sure which update broke it. I think I was trying smooth brightness change in 5.20.0 and it worked, so maybe some of the later updates.

Changing brightness via Energy Saving doesn't work either.

Also I tried lxqt-brightness. Lowering brightness worked fine, raising brightness did work, but looked like it was changing gamma rather than backlight intensity.

STEPS TO REPRODUCE
1. Start plasma
2. Use Fn+F2/F3 to change brightness

OBSERVED RESULT
Brightness does not change.

EXPECTED RESULT
Brightness should change.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Manjaro testing
KDE Plasma Version: 5.20.3
KDE Frameworks Version: 5.76.0
Qt Version: 5.15.1

Comment 1 elman 2020-11-24 08:48:51 UTC

I tried changing brightness in Windows 10 and it worked OK. So no hardware failure.

Comment 2 elman 2020-11-24 09:12:10 UTC

Booting with latest Kernel 5.4 LTS solved the issue. So it seems problem lies with kernel and not Plasma.

Comment 3 Christoph Feck 2020-11-24 09:34:24 UTC

Thanks for the update; changing status.