Bug 289495

Summary:	Screen brightness on Lenovo T510 does not work
Product:	[Unmaintained] solid	Reporter:	John Wheaton <johnwheaton2>
Component:	powermanagement-daemon	Assignee:	Dario Freddi <drf>
Status:	RESOLVED FIXED
Severity:	normal	CC:	afiestas, clearmartin
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Ubuntu
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description John Wheaton 2011-12-21 12:30:33 UTC

Version:           unspecified (using KDE 4.7.3) 
OS:                Linux

The screen brightness controls on a Lenovo T510 do not work.  Sometimes when adjusting the brightness up the KDE brightness OSD will display and show the setting increasing.  But nothing displays for the brightness decreasing.  But, no matter what, the actual screen brightness does not change.

Please let me know what additional information I can send.

Reproducible: Always

Steps to Reproduce:
Start KDE.
Login.
Adjust brightness up/down.

Actual Results:  
Nothing happens.

Expected Results:  
Brightness should change.

Comment 1 Alex Fiestas 2013-03-03 16:15:30 UTC

Is this still happening in KDE 4.10?

Comment 2 John Wheaton 2013-03-03 17:36:28 UTC

I am using Kubuntu 12.4.  I think there was a patch at some point in the LTS that included a fix to KDE for this.

IOW, this problem is resolved.  Thank you for checking on it!

Comment 3 Alex Fiestas 2013-03-05 19:54:50 UTC

Okey !

If for any reason this still happens once you update to the next LTS just reopen the bug :)

Comment 4 Martin Kostolný 2013-07-27 15:40:06 UTC

I am experiencing similar problem. I can change my display brightness but no brightness indicator is shown. The indicator only comes up when KDE Power Management itself changes brightness (e.g. dimming screen after set amount of minutes).

When I mix these two independent approaches (I change brightness by FN keys and KDE Power Management increases brightness e.g. because a key was pressed and screen was "idle-dimmed") -> screen brightness starts to flicker indefinitely until I put notebook to sleep.

I think this can be caused by storing brightness number into 2 different paths like:
/sys/class/backlight/intel_backlight/brightness
and
/sys/class/backlight/acpi_video0/brightness
...but I'm totally guessing, I did no research so far.

My rig is Lenovo T510, Arch Linux, KDE 4.10.5. I've experienced the same behaviour on Gentoo.