PM / QoS: Add function dev_pm_qos_read_value() (v3)

To read the current PM QoS value for a given device we need to
make sure that the device's power.constraints object won't be
removed while we're doing that.  For this reason, put the
operation under dev->power.lock and acquire the lock
around the initialization and removal of power.constraints.

Moreover, since we're using the value of power.constraints to
determine whether or not the object is present, the
power.constraints_state field isn't necessary any more and may be
removed.  However, dev_pm_qos_add_request() needs to check if the
device is being removed from the system before allocating a new
PM QoS constraints object for it, so make it use the
power.power_state field of struct device for this purpose.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index f2a25f18fde7..9bf62323aaf3 100644
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -1,3 +1,5 @@
+#include <linux/pm_qos.h>
+
 #ifdef CONFIG_PM_RUNTIME
 
 extern void pm_runtime_init(struct device *dev);
@@ -35,15 +37,21 @@ extern void device_pm_move_last(struct device *);
 static inline void device_pm_init(struct device *dev)
 {
         spin_lock_init(&dev->power.lock);
+        dev->power.power_state = PMSG_INVALID;
         pm_runtime_init(dev);
 }
 
+static inline void device_pm_add(struct device *dev)
+{
+        dev_pm_qos_constraints_init(dev);
+}
+
 static inline void device_pm_remove(struct device *dev)
 {
+        dev_pm_qos_constraints_destroy(dev);
         pm_runtime_remove(dev);
 }
 
-static inline void device_pm_add(struct device *dev) {}
 static inline void device_pm_move_before(struct device *deva,
                                          struct device *devb) {}
 static inline void device_pm_move_after(struct device *deva,