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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - GPU Hangs since Kernel-4.2 upgrade"
href="https://bugs.freedesktop.org/show_bug.cgi?id=91894#c3">Comment # 3</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - GPU Hangs since Kernel-4.2 upgrade"
href="https://bugs.freedesktop.org/show_bug.cgi?id=91894">bug 91894</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>libva did have a bug where they forgot to mark render targets and one of the
4.2 changes is a read-read optimisation. A hack like
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index a953d4975b8c..e4786eeca38f 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1033,7 +1033,7 @@ i915_gem_execbuffer_move_to_active(struct list_head
*vmas,
u32 old_write = obj->base.write_domain;
obj->dirty = 1; /* be paranoid */
- obj->base.write_domain = obj->base.pending_write_domain;
+ obj->base.write_domain = I915_GEM_DOMAIN_RENDER;
if (obj->base.write_domain == 0)
obj->base.pending_read_domains |=
obj->base.read_domains;
obj->base.read_domains = obj->base.pending_read_domains;
would disable the optimisation and hide the libva bug. Does that fix your hang?</pre>
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