On a fresh install of Ubuntu 11.04, running Unity, I can't adjust the brightness via Fn+Up/Down. The brightness panel will show, and increase/decrease accordingly, but the actual brightness never changes.
This is an issue I also had on 10.04. I used to fix this by adding this line
Option "RegistryDwords" "EnableBrightnessControl=1"
to my /etc/Xorg/xorg.conf in Section "Device". However it seems this is not working anymore. I also noticed the config file is much smaller that what I remember. Here is the whole file:
Section "Device" Identifier "Default Device" Option "NoLogo" "True" Option "RegistryDwords" "EnableBrightnessControl=1" EndSection
Should I use this line somewhere else ? or is there something else to fix ?
For reference, here is the original issue on 10.04: https://answers.launchpad.net/ubuntu/+source/xserver-xorg-video-nv/+question/109012