Commit eb119bd6 authored Dec 16, 2012 by Chris Wilson Committed by Daniel Vetter Dec 17, 2012

drm/i915: Access to snooped system memory through the GTT is incoherent

We ignore all the user requests to handle flushing to the GTT domain if
the user requests such on a snoopable bo, and as such access through the
GTT to such pages remains incoherent. The specs even warn that such
behaviour is undefined - a strong reason never to do so.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

parent 3f8c65d6

drivers/gpu/drm/i915/i915_gem.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -1341,6 +1341,12 @@ int i915_gem_fault(struct vm_area_struct vma, struct vm_fault vmf)

		trace_i915_gem_object_fault(obj, page_offset, true, write);

		/* Access to snoopable pages through the GTT is incoherent. */
		if (obj->cache_level != I915_CACHE_NONE && !HAS_LLC(dev)) {
		ret = -EINVAL;
		goto unlock;
		}

		/* Now bind it into the GTT if needed */
		ret = i915_gem_object_pin(obj, 0, true, false);
		if (ret)