[PATCH 01/11] drm/xe: Introduce xe_pm_runtime_get_noresume for inner callers

[Rodrigo Vivi]

Let's ensure that we have an option for inner callers that will
raise WARN if device is not active and not protected by outer callers.

Make this also a void function forcing every caller to unconditionally
put the reference back afterwards.

This will be very important for cases where we want to hold the
reference before scheduling a work in a queue. Then the work job
will be responsible for putting it back.

While at this, already convert a case from mem_access_ongoing where
it is not checking for the reference and put it back, what would
cause the underflow.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
Reviewed-by: Matthew Auld <matthew.auld at intel.com>
---
 drivers/gpu/drm/xe/xe_exec_queue.c |  2 +-
 drivers/gpu/drm/xe/xe_pm.c         | 20 ++++++++++++++++++++
 drivers/gpu/drm/xe/xe_pm.h         |  1 +
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c
index 6a83bc57826a..f69a9c99329c 100644
--- a/drivers/gpu/drm/xe/xe_exec_queue.c
+++ b/drivers/gpu/drm/xe/xe_exec_queue.c
@@ -128,7 +128,7 @@ static int __xe_exec_queue_init(struct xe_exec_queue *q)
 	 * already grabbed the rpm ref outside any sensitive locks.
 	 */
 	if (!(q->flags & EXEC_QUEUE_FLAG_PERMANENT) && (q->flags & EXEC_QUEUE_FLAG_VM || !q->vm))
-		drm_WARN_ON(&xe->drm, !xe_device_mem_access_get_if_ongoing(xe));
+		xe_pm_runtime_get_noresume(xe);
 
 	return 0;
 
diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
index 9fbb6f6c598a..847b263afe70 100644
--- a/drivers/gpu/drm/xe/xe_pm.c
+++ b/drivers/gpu/drm/xe/xe_pm.c
@@ -477,6 +477,26 @@ bool xe_pm_runtime_get_if_in_use(struct xe_device *xe)
 	return pm_runtime_get_if_in_use(xe->drm.dev) > 0;
 }
 
+/**
+ * xe_pm_runtime_get_noresume - Bump runtime PM usage counter without resuming
+ * @xe: xe device instance
+ *
+ * This function should be used in inner places where it is surely already
+ * protected by outer-bound callers of `xe_pm_runtime_get`.
+ * It will warn if not protected.
+ * The reference should be put back after this function regardless, since it
+ * will always bump the usage counter, regardless.
+ */
+void xe_pm_runtime_get_noresume(struct xe_device *xe)
+{
+      bool ref;
+
+      ref = xe_pm_runtime_get_if_in_use(xe);
+
+      if (drm_WARN(&xe->drm, !ref, "Missing outer runtime PM protection\n"))
+	      pm_runtime_get_noresume(xe->drm.dev);
+}
+
 /**
  * xe_pm_runtime_resume_and_get - Resume, then get a runtime_pm ref if awake.
  * @xe: xe device instance
diff --git a/drivers/gpu/drm/xe/xe_pm.h b/drivers/gpu/drm/xe/xe_pm.h
index 0cb38ca244fe..119b630ad1d1 100644
--- a/drivers/gpu/drm/xe/xe_pm.h
+++ b/drivers/gpu/drm/xe/xe_pm.h
@@ -31,6 +31,7 @@ int xe_pm_runtime_get_ioctl(struct xe_device *xe);
 void xe_pm_runtime_put(struct xe_device *xe);
 int xe_pm_runtime_get_if_active(struct xe_device *xe);
 bool xe_pm_runtime_get_if_in_use(struct xe_device *xe);
+void xe_pm_runtime_get_noresume(struct xe_device *xe);
 bool xe_pm_runtime_resume_and_get(struct xe_device *xe);
 void xe_pm_assert_unbounded_bridge(struct xe_device *xe);
 int xe_pm_set_vram_threshold(struct xe_device *xe, u32 threshold);
-- 
2.44.0