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authorRafael J. Wysocki <rjw@sisk.pl>2012-04-29 22:54:47 +0200
committerRafael J. Wysocki <rjw@sisk.pl>2012-05-01 21:28:43 +0200
commit23e0fc5ae64925e0ff1b6221b83dff1b217545df (patch)
treed22f7b9891242715238014e00f97646256bea053 /drivers/base
parent76e267d822f2913893ad210ba431607aa8e2af94 (diff)
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PM / QoS: Create device constraints objects on notifier registration
The current behavior of dev_pm_qos_add_notifier() makes device PM QoS notifiers less than useful. Namely, it silently returns success when called before any PM QoS constraints are added for the device, so the caller will assume that the notifier has been registered, but when someone actually adds some nontrivial constraints for the device eventually, the previous callers of dev_pm_qos_add_notifier() will not know about that and their notifier routines will not be executed (contrary to their expectations). To address this problem make dev_pm_qos_add_notifier() create the constraints object for the device if it is not present when the routine is called. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by : markgross <markgross@thegnar.org>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/power/qos.c19
1 files changed, 12 insertions, 7 deletions
diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
index 71855570922d..fd849a2c4fa8 100644
--- a/drivers/base/power/qos.c
+++ b/drivers/base/power/qos.c
@@ -352,21 +352,26 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
*
* Will register the notifier into a notification chain that gets called
* upon changes to the target value for the device.
+ *
+ * If the device's constraints object doesn't exist when this routine is called,
+ * it will be created (or error code will be returned if that fails).
*/
int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
{
- int retval = 0;
+ int ret = 0;
mutex_lock(&dev_pm_qos_mtx);
- /* Silently return if the constraints object is not present. */
- if (dev->power.constraints)
- retval = blocking_notifier_chain_register(
- dev->power.constraints->notifiers,
- notifier);
+ if (!dev->power.constraints)
+ ret = dev->power.power_state.event != PM_EVENT_INVALID ?
+ dev_pm_qos_constraints_allocate(dev) : -ENODEV;
+
+ if (!ret)
+ ret = blocking_notifier_chain_register(
+ dev->power.constraints->notifiers, notifier);
mutex_unlock(&dev_pm_qos_mtx);
- return retval;
+ return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);