I discovered a problem and I can't find here or via Google. I'm using 11.10.
When I'm running on AC I can adjust the brightness of my screen with Fn+F5 and Fn+F6 or by using the Systemsettings->Screen->Brightness-Slider.
But when my system is running on battery I can only set the brightness by using the slider. If I press Fn+F5 or Fn+F6 the brightness jumps to 100% or sometimes 90% no matter which key and how often I press it. but using the slider I can adjust it again.
I'm using a Dell Vostro 3350, using the i7 integrated HD3000, ATI switched off.
# cat /sys/kernel/debug/vgaswitcheroo/switch 0:IGD:+:Pwr:0000:00:02.0 1:DIS: :Off:0000:01:00.0
if this is important.
Any ideas how to fix this?
Edit: OK I don't know why, but the behavior changed. I can now only go one step up or down when the power cable is plugged in. like i start with 50%, i can go up to 60% and back to 50%(but not to 40%) or if i go from 50% to 40% and back i cant go to 60% brightness.
on battery only its still the same, max. brightness all the time, can only go down to 90%, at least it displays one step gone down.
with only power cable plugged in and battery not inside laptop in works like a charm.