[arch-general] xf86-video-ati, xbrightness and KMS bug

[Fess]

Hi guys.
I've switched to xf86-video-ati from fgrlx and have some troubles with
changing brightness level.
xbrightness tells me: "No outputs have backlight property". 
With fgrlx it worked like a charm.
If anyone have a solution - it will be great.

P.S.
My keyboard dead now, so i have to use discrete, and have no FN buttons.

I have asus x61s.
Video: Ati Radeon HD4570 and enabled KMS. Without KMS X won't start.
Kernel: 2.6.37-5
Driver: 6.14.0-1
xorg.conf.d file: http://paste.pocoo.org/show/338214/
-- 
With best wishes or hundreds of hate.