Confirmed noivalrange fixes the issue for me. Thanks Marek. If it helps i also
had the issue with the gl flicker in xbmc which Alex fixed recently in rc6. 

(In reply to comment #21)
> Setting the environment variable R600_DEBUG=noinvalrange should fix this.
> I'm still trying to figure out what's wrong with it. It looks like a
> synchronization issue, because doing a context flush in
> r600_buffer_transfer_unmap fixes it.