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On 11/28/2017 1:40 AM, Chris Wilson wrote:<br>
<blockquote type="cite"
cite="mid:151186200602.6046.15157037625800016943@mail.alporthouse.com">
<pre wrap="">Quoting <a class="moz-txt-link-abbreviated" href="mailto:John.C.Harrison@Intel.com">John.C.Harrison@Intel.com</a> (2017-11-28 09:10:59)
</pre>
<blockquote type="cite">
<pre wrap="">From: John Harrison <a class="moz-txt-link-rfc2396E" href="mailto:John.C.Harrison@Intel.com"><John.C.Harrison@Intel.com></a>
The call to enable signaling was occuring after the request had been
sent to the GuC for execution on the hardware. That means that it is
possible for the request to actually complete before the code to
enable signaling has executed.
</pre>
</blockquote>
<pre wrap="">
No, it wasn't, unless you had modified the code. Note also we switched
to a different scheme in upstream
-Chris
</pre>
</blockquote>
<br>
It was as of:<br>
<blockquote>commit d99c1a7aff71536e909f54709023dcc5d6b559c0<br>
Author: Chris Wilson <a class="moz-txt-link-rfc2396E" href="mailto:chris@chris-wilson.co.uk"><chris@chris-wilson.co.uk></a><br>
Date: Thu Mar 16 12:56:18 2017 +0000<br>
<br>
drm/i915/scheduler: emulate a scheduler for guc<br>
</blockquote>
<br>
The code introduced was:<br>
<blockquote>+ ...<br>
+ if (last && rq->ctx != last->ctx) {<br>
+ ...<br>
<b>+ nested_enable_signaling(last);</b><b><br>
</b>
+ port++;<br>
+ }<br>
+ ...<br>
<b>+ i915_guc_submit(rq);</b><b><br>
</b>+ last = rq;<br>
+ submit = true;<br>
+ }<br>
+ if (submit) {<br>
+ i915_gem_request_assign(&port->request,
last);<br>
<b>+ nested_enable_signaling(last);</b><b><br>
</b>+ engine->execlist_first = rb;<br>
+ }<br>
+ ...<br>
</blockquote>
<br>
That quite definitely calls nested_enable_signaling() after calling
i915_guc_submit(). It is either called on the last request submitted
for a given context or on the last request submitted overall. But in
either case it is only called after the actual submission occurs.<br>
<br>
Maybe that was not exactly 4.11, there might have been a few more
recent patches pulled in to this tree. It is definitely not latest
upstream though. And as I noted in the cover letter, moving to
latest upstream is not an option for them at this point.<br>
<br>
John.<br>
<br>
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