[Intel-gfx] [PATCH] drm/i915: Assert that we successfully downclock the GPU before suspend

[Chris Wilson]

Before suspending, we wait upon the outstanding GPU requests and flush
our pending idle handlers. This should downclock the GPU to its lowest
power state. Add a WARN to check that the delayed tasks were run and did
their job properly.

Suggested-by: Akash Goel <akash.goel at intel.com>
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 4a1ca7abd7f9..e4fa0bc62c10 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4669,6 +4669,11 @@ i915_gem_suspend(struct drm_device *dev)
 	cancel_delayed_work_sync(&dev_priv->mm.retire_work);
 	flush_delayed_work(&dev_priv->mm.idle_work);
 
+	/* Assert that we sucessfully flushed all the work and
+	 * reset the GPU back to its idle, low power state.
+	 */
+	WARN_ON(dev_priv->mm.busy);
+
 	return 0;
 
 err:
-- 
2.1.3