[Intel-gfx] [PATCH 5/5] drm/i915: Stop spinning for DROP_IDLE (debugfs/i915_drop_caches)

Chris Wilson chris at chris-wilson.co.uk
Tue Apr 30 15:18:57 UTC 2019

If the user is racing a call to debugfs/i915_drop_caches with ongoing
submission from another thread/process, we may never end up idling the
GPU and be uninterruptibly spinning in debugfs/i915_drop_caches trying
to catch an idle moment.

Just flush the work once, that should be enough to park the system under
correct conditions. Outside of those we either have a driver bug or the
user is racing themselves. Sadly, because the user may be provoking the
unwanted situation we can't put a warn here to attract attention to a
probable bug.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
 drivers/gpu/drm/i915/i915_debugfs.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 7e8898d0b78b..2ecefacb1e66 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3933,9 +3933,7 @@ i915_drop_caches_set(void *data, u64 val)
 	if (val & DROP_IDLE) {
-		do {
-			flush_delayed_work(&i915->gem.retire_work);
-		} while (READ_ONCE(i915->gt.awake));
+		flush_delayed_work(&i915->gem.retire_work);

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