[Intel-gfx] [PATCH 2/3] drm/i915: Fix incorrect assert about pending power domain async-put work

[Imre Deak]

It's possible that an already dequeued put_async_work() will release the
reference (*) that was put asynchronously after the dequeue happened.
This leaves an async-put work pending, without any reference to release.
A subsequent async-put may trigger the

drm_WARN_ON(!queue_delayed_work(&power_domains->async_put_work));

warn due to async_put_work() still pending. To avoid the warn, cancel
the pending async_put_work() when releasing the reference at (*) above.

Fixes: https://gitlab.freedesktop.org/drm/intel/-/issues/3421
Fixes: https://gitlab.freedesktop.org/drm/intel/-/issues/2289
Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display_power.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index 2f7d1664c4738..a95bbf23e6b7c 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -2263,6 +2263,12 @@ intel_display_power_put_async_work(struct work_struct *work)
 			fetch_and_zero(&power_domains->async_put_domains[1]);
 		queue_async_put_domains_work(power_domains,
 					     fetch_and_zero(&new_work_wakeref));
+	} else {
+		/*
+		 * Cancel the work that got queued after this one got dequeued,
+		 * since here we released the corresponding async-put reference.
+		 */
+		cancel_delayed_work(&power_domains->async_put_work);
 	}
 
 out_verify:
-- 
2.27.0