[Intel-gfx] [PATCH] drm/i915/gem: Serialise object before changing cache-level

[Chris Wilson]

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 at chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti at intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_domain.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_domain.c b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
index 88ab7e71f36c..65f1851e2863 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_domain.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
@@ -190,6 +190,13 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
 	if (obj->cache_level == cache_level)
 		return 0;
 
+	ret = i915_gem_object_wait(obj,
+				   I915_WAIT_INTERRUPTIBLE |
+				   I915_WAIT_ALL,
+				   MAX_SCHEDULE_TIMEOUT);
+	if (ret)
+		return ret;
+
 	ret = i915_gem_object_lock_interruptible(obj);
 	if (ret)
 		return ret;
-- 
2.24.0