The buttons for changing the backlight brightness on my laptop (Fn-F10, Fn-Cursor-Up/Down)
stop working after starting the X server. They do work when I boot to a text console. Once
I start the X server, they stop working. They do not work again even if I switch back to
a text console or shut down the X server. The only way to make them work again is to
reboot the machine or do a suspend-to-RAM & wakeup. (After wakeup my system does not switch
back to the X tty but shows the first text console. "vbetool post" and
"vbetool vbestate restore" are called right after wakeup automatically.)

The bug is not new (e.g. not introduced with 6.8.0). This bug was present as long a I
run Xorg on my laptop (more than 1 year).

The bug does not only affect the brightness-buttons, but all Fn-combos (for example
Fn-F4 to switch between internal/external display).

Till wrote:

It's often recommended that you do NOT use these buttons because they
may change things in the back of the video driver and thus break things
(especially when talking about switching between internal/external
display). You could try the ati driver from experimental just in case,
but I don't expect much there...

Brice

* Brice Goglin wrote:

What else do you suggest to change the brightness? Is there any
working tool? (I tried xrandr and APCI, but my card does not seem to
"offer" anything to set the brightness.)

Till.