drm/i915: Skip final clflush if LLC is coherent

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@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161118211747.25197-2-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b6ad1bae5a158e6313797fdc4a227c594fc5affa..902fa427c19612bac15dd0540f4ebde846da7943 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -229,7 +229,8 @@ __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;