Radeon KMS extremely slow on RS600

[Dariem Pérez Herrera]

Hello,
I'm using a GPU RS600. This has always been a problematic GPU for free 
radeon drivers since I have my notebook (more than a year). I've never 
riched more than 320 fps, and as average I'm always running at 190 fps 
more or less. Right now, I'm testing latest kernel RC with radeon KMS 
feature activated, latest xf86-video-ati from git, latest libdrm, latest 
mesa. I'm having a very slow speed experience with my graphics:  55 fps. 
I'm also noting some totally white screens in certain times, during 
initializations of graphic modes, but later it recovers (but again, with 
very slow speed). I found this in my log:

(II) [KMS] drm report modesetting isn't supported.

I'm willing to test any patch, any release, anything, whatever you do to 
improve support for my card. I can even code with some guidance. Thanks 
in advance.

best regards,

Dariem