[Mesa-dev] [PATCH 0/10] Tessellation shaders for Gen7/7.5.

Kenneth Graunke kenneth at whitecape.org
Thu Dec 24 17:34:18 PST 2015

This morning, I woke up and somehow "knew" what was causing my HS GPU hangs
on Gen7/7.5.  It turns out I was (completely) wrong, but through some
miraculous series of illogical leaps, I arrived at a solution anyway.

I don't honestly know how I got it working on Christmas Eve after
failing to figure it out for months on end.  After exhausting every bit
of documentation and every tool available, and finding zero information,
somehow randomly flailing in the dark resulted in a solution, today of
all days.  Honestly, I had pretty much no hope for figuring this out,
so I'm relieved to have it working at last...

It turns out that setting interleave on the EOT URB write does bad things.
Fixing this fixed all the GPU hangs when releasing inputs one at a time,
I then added back the ability to release inputs in pairs, which caused
more GPU hangs.  It turned out I needed to be more careful and enable
both halves.

Everything seems to be working just fine now, so let's turn it on.


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