[PATCH for-v5.15.y 1/2] PM: runtime: Have devm_pm_runtime_enable() handle pm_runtime_dont_use_autosuspend()

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From: Douglas Anderson <dianders@xxxxxxxxxxxx>

[ Upstream commit b4060db9251f919506e4d672737c6b8ab9a84701 ]

The PM Runtime docs say:

  Drivers in ->remove() callback should undo the runtime PM changes done
  in ->probe(). Usually this means calling pm_runtime_disable(),
  pm_runtime_dont_use_autosuspend() etc.

>From grepping code, it's clear that many people aren't aware of the
need to call pm_runtime_dont_use_autosuspend().

When brainstorming solutions, one idea that came up was to leverage
the new-ish devm_pm_runtime_enable() function. The idea here is that:

 * When the devm action is called we know that the driver is being
   removed. It's the perfect time to undo the use_autosuspend.

 * The code of pm_runtime_dont_use_autosuspend() already handles the
   case of being called when autosuspend wasn't enabled.

Suggested-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Stable-dep-of: 3d07a411b4fa ("drm/msm/dsi: Use pm_runtime_resume_and_get to prevent refcnt leaks")
Signed-off-by: Amit Pundir <amit.pundir@xxxxxxxxxx>
---
 drivers/base/power/runtime.c | 5 +++++
 include/linux/pm_runtime.h   | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 5824d41a0b74..6699096ff2fa 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1479,11 +1479,16 @@ EXPORT_SYMBOL_GPL(pm_runtime_enable);
 
 static void pm_runtime_disable_action(void *data)
 {
+	pm_runtime_dont_use_autosuspend(data);
 	pm_runtime_disable(data);
 }
 
 /**
  * devm_pm_runtime_enable - devres-enabled version of pm_runtime_enable.
+ *
+ * NOTE: this will also handle calling pm_runtime_dont_use_autosuspend() for
+ * you at driver exit time if needed.
+ *
  * @dev: Device to handle.
  */
 int devm_pm_runtime_enable(struct device *dev)
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index 90eaff8b78fc..7efb10518313 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -542,6 +542,10 @@ static inline void pm_runtime_disable(struct device *dev)
  * Allow the runtime PM autosuspend mechanism to be used for @dev whenever
  * requested (or "autosuspend" will be handled as direct runtime-suspend for
  * it).
+ *
+ * NOTE: It's important to undo this with pm_runtime_dont_use_autosuspend()
+ * at driver exit time unless your driver initially enabled pm_runtime
+ * with devm_pm_runtime_enable() (which handles it for you).
  */
 static inline void pm_runtime_use_autosuspend(struct device *dev)
 {
-- 
2.25.1





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