(In reply to Nicolas Werner from comment #69)
> 
> I also have the same problem. (same notebook, so not surprising)
> 
> I tried everything you recommended (in comment #65), in order, nothing
> helps. Any more suggestions?

Does this patch help?
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=1c9498425453bb65ef339a57705c5ef59fe1541d

> 
> Btw, I'm using OpenSUSE, so Kernel 3.16.6.
> 
> Also xrandr output is much shorter than the ones posted here, is that normal
> when you use modeset=0?

Yes.  When you set modeset=0 you are effectively disabling the radeon driver so
you end up with vesa or efifb or some other platform driver rather than the
native driver.