[PATCH 03/11] drm/i915: Wait until the intel_wakeref idle callback is complete

[Chris Wilson]

When waiting for idle, serialise with any ongoing callback so that it
will have completed before completing the wait.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_wakeref.c | 11 +++++++++--
 drivers/gpu/drm/i915/intel_wakeref.h | 14 ++++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_wakeref.c b/drivers/gpu/drm/i915/intel_wakeref.c
index 8084cded62db..0d1d9e485500 100644
--- a/drivers/gpu/drm/i915/intel_wakeref.c
+++ b/drivers/gpu/drm/i915/intel_wakeref.c
@@ -100,8 +100,15 @@ void __intel_wakeref_init(struct intel_wakeref *wf,
 
 int intel_wakeref_wait_for_idle(struct intel_wakeref *wf)
 {
-	return wait_var_event_killable(&wf->wakeref,
-				       !intel_wakeref_is_active(wf));
+	int err;
+
+	err = wait_var_event_killable(&wf->wakeref,
+				      !intel_wakeref_is_active(wf));
+	if (err)
+		return err;
+
+	intel_wakeref_unlock_wait(wf);
+	return 0;
 }
 
 static void wakeref_auto_timeout(struct timer_list *t)
diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
index ff4876093541..eeac3e7dfafe 100644
--- a/drivers/gpu/drm/i915/intel_wakeref.h
+++ b/drivers/gpu/drm/i915/intel_wakeref.h
@@ -160,6 +160,20 @@ intel_wakeref_unlock(struct intel_wakeref *wf)
 	mutex_unlock(&wf->mutex);
 }
 
+/**
+ * intel_wakeref_unlock_wait: Wait until the active callback is complete
+ * @wf: the wakeref
+ *
+ * Waits for the active callback (under the @wf->mtuex) is complete.
+ */
+static inline void
+intel_wakeref_unlock_wait(struct intel_wakeref *wf)
+{
+	mutex_lock(&wf->mutex);
+	mutex_unlock(&wf->mutex);
+	flush_work(&wf->work);
+}
+
 /**
  * intel_wakeref_is_active: Query whether the wakeref is currently held
  * @wf: the wakeref
-- 
2.24.0