(In reply to comment #15)
> A patch referencing this bug report has been merged in Linux v3.7-rc1:
> 
> commit bced76f27165ca7733437715185c3a1aa526f7a1
> Author: Alex Deucher <alexander.deucher@amd.com>
> Date:   Fri Sep 14 09:45:50 2012 -0400
> 
>     drm/radeon: restore backlight level on resume

appears to be the same patch as mentioned in comment #10, and (at least for me)
still does not fix the issue