[Intel-gfx] [PATCH v2] PM / Runtime: Introduce pm_runtime_get_noidle

[Joonas Lahtinen]

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.

v2:
- Fix inconsistent return value when !CONFIG_PM.
- Update documentation for bool return value

Signed-off-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Reported-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: "Rafael J. Wysocki" <rjw at rjwysocki.net>
Cc: linux-pm at vger.kernel.org
---
 Documentation/power/runtime_pm.txt | 4 ++++
 include/linux/pm_runtime.h         | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 0784bc3..a0cbfe1 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -363,6 +363,10 @@ 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
 
+  bool pm_runtime_get_noidle(struct device *dev);
+    - increment the device's usage counter if it is not 0 and return
+      whether usage counter was incremented
+
   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..8f429bc 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 bool pm_runtime_get_noidle(struct device *dev)
+{
+	return atomic_add_unless(&dev->power.usage_count, 1, 0) > 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