On Wed, Feb 01, 2012 at 10:26:45PM +0100, Daniel Vetter wrote: > Chris Wilson and me have again stared at funny error states and it's > been pretty clear from the start that something was seriously amiss. > The seqnos last seen by the cpu were a few hundred behind those that > the gpu could have possibly emitted last before it died ... > > Chris now tracked it down (hopefully, definit verdict's still out), > but in hindsight we'd have found the bug by simply dumping the cpu > side tracking of the ring head and tail registers. > > Fix this and prevent an identical time-waster in the future. > > Because the hangs always involved semaphores in one way or another, > we've tried to dump the mbox registers, but couldn't find any > inconsistencies. Still, dump them too. How about we only do this if semaphores are actually enabled? I think that will eliminate potential confusion.
