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<body><span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [APL BSW BDW] [BAT execlists] Sporadic - gem_exec_suspend basic-s4 GPU hang after resume"
href="https://bugs.freedesktop.org/show_bug.cgi?id=96526">bug 96526</a>
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<table border="1" cellspacing="0" cellpadding="8">
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<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
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<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>FIXED
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<td style="text-align:right;">Status</td>
<td>ASSIGNED
</td>
<td>RESOLVED
</td>
</tr></table>
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [APL BSW BDW] [BAT execlists] Sporadic - gem_exec_suspend basic-s4 GPU hang after resume"
href="https://bugs.freedesktop.org/show_bug.cgi?id=96526#c58">Comment # 58</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [APL BSW BDW] [BAT execlists] Sporadic - gem_exec_suspend basic-s4 GPU hang after resume"
href="https://bugs.freedesktop.org/show_bug.cgi?id=96526">bug 96526</a>
from <span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span></b>
<pre>commit bafb2f7d4755bf1571bd5e9a03b97f3fc4fe69ae
Author: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
Date: Wed Sep 21 14:51:08 2016 +0100
drm/i915/execlists: Reset RING registers upon resume
There is a disparity in the context image saved to disk and our own
bookkeeping - that is we presume the RING_HEAD and RING_TAIL match our
stored ce->ring->tail value. However, as we emit WA_TAIL_DWORDS into the
ring but may not tell the GPU about them, the GPU may be lagging behind
our bookkeeping. Upon hibernation we do not save stolen pages, presuming
that their contents are volatile. This means that although we start
writing into the ring at tail, the GPU starts executing from its HEAD
and there may be some garbage in between and so the GPU promptly hangs
upon resume.
Testcase: igt/gem_exec_suspend/basic-S4
Bugzilla: <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [APL BSW BDW] [BAT execlists] Sporadic - gem_exec_suspend basic-s4 GPU hang after resume"
href="show_bug.cgi?id=96526">https://bugs.freedesktop.org/show_bug.cgi?id=96526</a>
Signed-off-by: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
Reviewed-by: Joonas Lahtinen <<a href="mailto:joonas.lahtinen@linux.intel.com">joonas.lahtinen@linux.intel.com</a>>
Link:
<a href="http://patchwork.freedesktop.org/patch/msgid/20160921135108.29574-3-chris@chris-wilson.co.uk">http://patchwork.freedesktop.org/patch/msgid/20160921135108.29574-3-chris@chris-wilson.co.uk</a></pre>
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