[Intel-gfx] [PATCH 2/2] drm/i915: Skip final clflush if LLC is coherent

[Chris Wilson]

If the LLC is coherent with the object, we do not need to worry about
whether main memory and cache mismatch when we hand the object back to
the system.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 4931bfcff2a2..3b021e9e3379 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -228,7 +228,8 @@ __i915_gem_object_release_shmem(struct drm_i915_gem_object *obj,
 	if (obj->mm.madv == I915_MADV_DONTNEED)
 		obj->mm.dirty = false;
 
-	if ((obj->base.read_domains & I915_GEM_DOMAIN_CPU) == 0)
+	if ((obj->base.read_domains & I915_GEM_DOMAIN_CPU) == 0 &&
+	    !cpu_cache_is_coherent(obj->base.dev, obj->cache_level))
 		drm_clflush_sg(pages);
 
 	obj->base.read_domains = I915_GEM_DOMAIN_CPU;
-- 
2.10.2