drm/i915: Unconditionally flush any chipset buffers before execbuf

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If userspace is asynchronously streaming into the batch or other
execobjects, we may not flush those writes along with a change in cache
domain (as there is no change). Therefore those writes may end up in
internal chipset buffers and not visible to the GPU upon execution. We
must issue a flush command or otherwise we encounter incoherency in the
batchbuffers and the GPU executing invalid commands (i.e. hanging) quite
regularly.

v2: Throw a paranoid wmb() into the general flush so that we remain
consistent with before.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90841
Fixes: 1816f92363 ("drm/i915: Support creation of unbound wc user...")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Akash Goel <akash.goel@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Tested-by: Matti Hämäläinen <ccr@tnsp.org>
Cc: stable@vger.kernel.org
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-1-chris@chris-wilson.co.uk
(cherry picked from commit 600f436801)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

...

This commit is contained in:

Chris Wilson 2016-08-18 17:16:40 +01:00 • committed by Jani Nikula

parent c7aca235aa

commit dcd79934b0

2 changed files with 4 additions and 10 deletions

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1

drivers/gpu/drm/i915/i915_drv.h

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13

drivers/gpu/drm/i915/i915_gem_execbuffer.c

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