Black screen with AMD A4-3300 support

Hi,

I have a new ASUS K53TA notebook with AMD A4-3300 CPU and an extra Radeon HD6550M. I installed Fedora 16 on it but I get only black screen even during installation unless booted with nomodeset. But it's only VESA so there's no acceleration and there's no native LCD 1366x768 resolution, only 1024x768, so it's a bit blurry.

The machine boots up and I can login via ssh so I can debug it. dmesg and Xorg.0.log says the integrated video is recognized and handled. Only the screen is black. dmesg says something about not being able to determine initial brightness setting.

Can anyone help me to get it to display X with KMS?

Thanks in advance, Zoltán Böszörményi