under the device's power directory.
Notification mechanisms:
-The per-device PM QoS framework has 2 different and distinct notification trees:
-a per-device notification tree and a global notification tree.
+The per-device PM QoS framework has a per-device notification tree.
int dev_pm_qos_add_notifier(device, notifier):
Adds a notification callback function for the device.
int dev_pm_qos_remove_notifier(device, notifier):
Removes the notification callback function for the device.
-int dev_pm_qos_add_global_notifier(notifier):
-Adds a notification callback function in the global notification tree of the
-framework.
-The callback is called when the aggregated value for any device is changed
-(for resume latency device PM QoS only).
-
-int dev_pm_qos_remove_global_notifier(notifier):
-Removes the notification callback function from the global notification tree
-of the framework.
-
Active state latency tolerance