(In reply to Christian Zigotzky from comment #17)
> (In reply to Alex Deucher from comment #4)
> > Hardly anything in the radeon driver has changed in the last few years. 
> > You'd really need to bisect.  Also, can you attach a full dmesg (full logs
> > not just filtered for radeon or drm) output from the failed and working
> > cases?
> 
> I have found some Radeon changes in these DRM updates:
> 
> -rw-r--r--	drivers/gpu/drm/radeon/r300.c	4			
> -rw-r--r--	drivers/gpu/drm/radeon/r420.c	1			
> -rw-r--r--	drivers/gpu/drm/radeon/radeon.h	3			
> -rw-r--r--	drivers/gpu/drm/radeon/radeon_cs.c	4			
> -rw-r--r--	drivers/gpu/drm/radeon/radeon_gem.c	2			
> -rw-r--r--	drivers/gpu/drm/radeon/radeon_legacy_tv.c 10			
> -rw-r--r--	drivers/gpu/drm/radeon/radeon_object.c	2			
> -rw-r--r--	drivers/gpu/drm/radeon/radeon_ttm.c	65			
> -rw-r--r--	drivers/gpu/drm/radeon/radeon_vm.c

Someone with access to the hw and the platform would have to go through the
changes and see what broke it.  A bisect would be an easy way to do it.  Also,
it's not necessarily a drm change.  It could have been a bad interaction with
some other change elsewhere in the kernel.