From: Chris Wilson Date: Thu, 14 Mar 2013 15:52:05 +0000 (+0200) Subject: drm/i915: Resurrect ring kicking for semaphores, selectively X-Git-Tag: omap-for-v3.10/dt-fixes-for-merge-window~55^2~60^2~26 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a24a11e6b4e96bca817f854e0ffcce75d3eddd13;p=pandora-kernel.git drm/i915: Resurrect ring kicking for semaphores, selectively 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 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 Signed-off-by: Mika Kuoppala Cc: Daniel Vetter Cc: Ben Widawsky Acked-by: Ben Widawsky Signed-off-by: Daniel Vetter --- Reading git-diff-tree failed