Hi,

I'm a recent Linux convert, and have installed Mint12 Main edition on my laptop, then installed KDE 4.8 on top of it.

I used to be able to adjust the screen brightness at the login screen and sleep the laptop. I don't recall trying to change the brightness inside KDE though. Then I updated my BIOS after installing PAE (to get all my 4GB of RAM recognized). I think after that I lost the ability to adjust the brightness in KDE as well as put laptop to sleep. I can move the brightness slider around and I get the OSD but nothing happens. When I try sleep, a notification pops up saying KDE is locking the screen, then the screen goes black, and then just stays there, it does not power off.

I am, however, able to adjust the screen brightness in Gnome (gnome3), so the issue may have nothing to do with the BIOS update.

Power management is enabled, and I even tried editing the xorg config file to enable brightness control (after which I could not boot into Linux at all). I've already reinstalled everything (except for the home partition), Mint12, then KDE 4.8.

Would appreciate any help. Thanks.

MSI CR400
Intel Core 2 Duo T6500 2.10Ghz
2GB Memory
Nvidia GeForce 8200M G
Linux 3.0.0-15-generic-PAE
Linux Mint 12 Main Edition
KDE 4.8.o

Well, I ended up just installing the Mint 12 KDE version (KDE 4.7.4). Brightness function keys work now. Sleep still doesn't, but that likely has something to do with the (sadly irreversible) BIOS update I did.

Edit: The BIOS update may have had something to do with KDE not being able to put laptop to sleep anymore, but it should still be able to despite it, as I booted into my Windows XP partition and was able to put the laptop to sleep (standby) from there. In Linux Mint/KDE, the screen just goes black after it's locked, then about 30 seconds later powers off.

First of all, welcome to KDE and the KDE Forums!

I don't think your issue with the sleep function is a problem with KDE software. I suggest that you also post a topic in the Linux Mint forums, where you're more likely to receive help.

Thanks for the welcome.

I can put the laptop to sleep from KDE only if I use the console (sudo /etc/acpi/sleepbtn.sh). If I go Kickoff Launcher--> Leave --> Sleep, screen locks, goes black then after some time completely powers off. If no other user is having the same issue then I guess it does have something to do with Linux Mint's implementation of KDE.

Loving KDE (despite the above and me feeling it's a bit bloated).

same problem here. Using Fedora 16 + KDE 4.8 and nvidiabl module to control backlight. It works with Gnome like a charme but with KDE no way to get it up (I had the same issue with Kubuntu 11.10). Any chance to solve this issue?
Thanks in advance

For NVidia users, please see https://bugs.kde.org/show_bug.cgi?id=261341
ATI users could possibly be affected by the same issue.

A system with a functioning Polkit installation appears to be required.