(In reply to comment #2)
> (In reply to comment #0)
> > 
> > I did a bisect and found that this commit introduced the corruption:
> > 
> > http://cgit.freedesktop.org/~agd5f/linux/commit/?h=drm-fixes-3.
> > 11&id=7ad8d0687bb5030c3328bc7229a3183ce179ab25
> 
> Prior to that commit, the driver didn't actually change clock levels.
> 
> Does it work any better if you build radeon as a module rather than building
> it into the kernel?

Well I think I'm already building radeon as a module since I have:
CONFIG_DRM=m
CONFIG_DRM_RADEON=m

or am I missing something?