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Diffstat (limited to 'Documentation/power/pm_qos_interface.txt')
| -rw-r--r-- | Documentation/power/pm_qos_interface.txt | 37 |
1 files changed, 16 insertions, 21 deletions
diff --git a/Documentation/power/pm_qos_interface.txt b/Documentation/power/pm_qos_interface.txt index 483632087788..22cb8f51182a 100644 --- a/Documentation/power/pm_qos_interface.txt +++ b/Documentation/power/pm_qos_interface.txt @@ -89,16 +89,16 @@ node. 2. PM QoS per-device latency and flags framework For each device, there are two lists of PM QoS requests. One is maintained -along with the aggregated target of latency value and the other is for PM QoS -flags. Values are updated in response to changes of the request list. +along with the aggregated target of resume latency value and the other is for +PM QoS flags. Values are updated in response to changes of the request list. -Target latency value is simply the minimum of the request values held in the -parameter list elements. The PM QoS flags aggregate value is a gather (bitwise -OR) of all list elements' values. Two device PM QoS flags are defined currently: -PM_QOS_FLAG_NO_POWER_OFF and PM_QOS_FLAG_REMOTE_WAKEUP. +Target resume latency value is simply the minimum of the request values held in +the parameter list elements. The PM QoS flags aggregate value is a gather +(bitwise OR) of all list elements' values. Two device PM QoS flags are defined +currently: PM_QOS_FLAG_NO_POWER_OFF and PM_QOS_FLAG_REMOTE_WAKEUP. -Note: the aggregated target value is implemented as an atomic variable so that -reading the aggregated value does not require any locking mechanism. +Note: the aggregated target value is implemented in such a way that reading the +aggregated value does not require any locking mechanism. From kernel mode the use of this interface is the following: @@ -137,14 +137,14 @@ Add a PM QoS request for the first direct ancestor of the given device whose power.ignore_children flag is unset. int dev_pm_qos_expose_latency_limit(device, value) -Add a request to the device's PM QoS list of latency constraints and create -a sysfs attribute pm_qos_resume_latency_us under the device's power directory -allowing user space to manipulate that request. +Add a request to the device's PM QoS list of resume latency constraints and +create a sysfs attribute pm_qos_resume_latency_us under the device's power +directory allowing user space to manipulate that request. void dev_pm_qos_hide_latency_limit(device) Drop the request added by dev_pm_qos_expose_latency_limit() from the device's -PM QoS list of latency constraints and remove sysfs attribute pm_qos_resume_latency_us -from the device's power directory. +PM QoS list of resume latency constraints and remove sysfs attribute +pm_qos_resume_latency_us from the device's power directory. int dev_pm_qos_expose_flags(device, value) Add a request to the device's PM QoS list of flags and create sysfs attributes @@ -163,7 +163,7 @@ a per-device notification tree and a global notification tree. int dev_pm_qos_add_notifier(device, notifier): Adds a notification callback function for the device. The callback is called when the aggregated value of the device constraints list -is changed. +is changed (for resume latency device PM QoS only). int dev_pm_qos_remove_notifier(device, notifier): Removes the notification callback function for the device. @@ -171,14 +171,9 @@ 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. +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. - - -From user mode: -No API for user space access to the per-device latency constraints is provided -yet - still under discussion. - |