[PATCH 1/3] PM / Runtime: Introduce pm_runtime_get_noidle

[Joonas Lahtinen <joonas.lahtinen@linux.intel.com>]

Introduce pm_runtime_get_noidle to for situations where it is not
desireable to touch an idling device. One use scenario is periodic
hangchecks performed by the drm/i915 driver which can be omitted
on a device in a runtime idle state.

Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
---
 Documentation/power/runtime_pm.txt | 3 +++
 include/linux/pm_runtime.h         | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 0784bc3..4545399 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -363,6 +363,9 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
   void pm_runtime_get_noresume(struct device *dev);
     - increment the device's usage counter
 
+  int pm_runtime_get_noidle(struct device *dev);
+    - increment the device's usage counter if it was not 0 and return it
+
   int pm_runtime_get(struct device *dev);
     - increment the device's usage counter, run pm_request_resume(dev) and
       return its result
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index 3bdbb41..ae34f5e 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -66,6 +66,11 @@ static inline void pm_runtime_get_noresume(struct device *dev)
 	atomic_inc(&dev->power.usage_count);
 }
 
+static inline int pm_runtime_get_noidle(struct device *dev)
+{
+	return atomic_add_unless(&dev->power.usage_count, 1, 0);
+}
+
 static inline void pm_runtime_put_noidle(struct device *dev)
 {
 	atomic_add_unless(&dev->power.usage_count, -1, 0);
@@ -153,6 +158,7 @@ static inline void pm_runtime_forbid(struct device *dev) {}
 
 static inline bool pm_children_suspended(struct device *dev) { return false; }
 static inline void pm_runtime_get_noresume(struct device *dev) {}
+static inline bool pm_runtime_get_noidle(struct device *dev) { return true; }
 static inline void pm_runtime_put_noidle(struct device *dev) {}
 static inline bool device_run_wake(struct device *dev) { return false; }
 static inline void device_set_run_wake(struct device *dev, bool enable) {}
-- 
2.4.3

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