Cacheline dirt following 8b1c78e06e61 ("drm/i915: Avoid calling i915_gem_object_unbind holding object lock")

The effect seems to be reduced number of cache_dirties

i915_gem_object_pin_to_display_plane:
+ obj->cache_dirty = true;
  i915_gem_object_flush_if_display(obj);

commit 7a90f89904afe66ff029bd784679aa293baacb72 (HEAD -> drm-intel-next-queued, drm-intel/for-linux-next, drm-intel/drm-intel-next-queued)
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Fri Dec 13 22:31:40 2019 +0000

    drm/i915/gem: Serialise object before changing cache-level
    
    Wait for the object to be idle before changing its cache-level and
    unbinding. This was dropped as supposedly superfluous from commit
    8b1c78e06e61 ("drm/i915: Avoid calling i915_gem_object_unbind holding
    object lock"), but it turns out to prevent some cache dirt escaping.
    Smells like papering over a race...
    
    Closes: https://gitlab.freedesktop.org/drm/intel/issues/820
    Fixes: 8b1c78e06e61 ("drm/i915: Avoid calling i915_gem_object_unbind holding object lock")
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
    Cc: Andi Shyti <andi.shyti@intel.com>
    Acked-by: Andi Shyti <andi.shyti@intel.com>
    Link: https://patchwork.freedesktop.org/patch/msgid/20191213223140.1830738-1-chris@chris-wilson.co.uk

closed