On Thu, Mar 14, 2013 at 05:52:05PM +0200, Mika Kuoppala wrote: > From: Chris Wilson <chris at chris-wilson.co.uk> > > Once we thought we got semaphores working, we disabled kicking the ring > if hangcheck fired whilst waiting upon a ring as it was doing more harm > than good: > > commit 4e0e90dcb8a7df1229c69e30abebb59b0b3c2a1f > Author: Daniel Vetter <daniel.vetter at ffwll.ch> > Date: Wed Dec 14 13:56:58 2011 +0100 > > drm/i915: kicking rings stuck on semaphores considered harmful > > However, life is never that easy and semaphores are still causing > problems whereby the value written by one ring (bcs) is not being > propagated to the waiter (rcs). Thus the waiter never wakes up and we > declare the GPU hung, which often has unfortunate consequences, even if > we successfully reset the GPU. > > But the GPU is idle as it has completed the work, just didn't notify its > clients. So we can detect the incomplete wait during hang check and > probe the target ring to see if has indeed emitted the breadcrumb seqno > following the work and then and only then kick the waiter. > > Based on a suggestion by Ben Widawsky. > > v2: cross-check wait with iphdr. fix signaller calculation. > > References: https://bugs.freedesktop.org/show_bug.cgi?id=54226 > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk> > Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com> > Cc: Daniel Vetter <daniel.vetter at ffwll.ch> > Cc: Ben Widawsky <ben at bwidawsk.net> > Acked-by: Ben Widawsky <ben at bwidawsk.net> I'll throw in the towel, let's all hail duct-tape. Queued for -next, thanks for the patch. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch
