(In reply to Michel Dänzer from comment #6)
> Please attach the output of dmesg, including all the drm/radeon
> initialization messages.

I suspect you need one when hang happens, I'm trying really hard to make it
hang with the patch from Alex but it seems that patch did the trick, there are
no more hangs. But I'll keep trying, just to be sure.
Although it should have happened by now.

Anyway, if you need dmesg when bug happens I'll do that one later, for now
here's the current one with no hangs :
https://bugs.freedesktop.org/attachment.cgi?id=117136