Documentation/power/pm_qos_interface.rst

2 PM Quality Of Service Interface
7 one of the parameters.
11  * The per-device PM QoS framework provides the API to manage the
12    per-device latency constraints and PM QoS flags.
20 A global list of CPU latency QoS requests is maintained along with an aggregated
22 to the request list or elements of the list.  For CPU latency QoS, the
23 aggregated target value is simply the min of the request values held in the list
29 From kernel space the use of this interface is simple:
35   Clients of PM QoS need to save the returned handle for future use in other
45   and call the notification tree if the target was changed as a result of
69 cleanup of a process, the interface requires the process to register its
87 2. PM QoS per-device latency and flags framework
90 For each device, there are three lists of PM QoS requests. Two of them are
91 maintained along with the aggregated targets of resume latency and active
93 Values are updated in response to changes of the request list.
95 The target values of resume latency and active state latency tolerance are
96 simply the minimum of the request values held in the parameter list elements.
97 The PM QoS flags aggregate value is a gather (bitwise OR) of all list elements'
104 From kernel mode the use of this interface is the following:
110   Clients of dev_pm_qos need to save the handle for future use in other
120   and call the notification trees if the target was changed as a result of
127   Check PM QoS flags of the given device against the given mask of flags.
128   The meaning of the return values is as follows:
138 		or the list of requests is empty.
141   Add a PM QoS request for the first direct ancestor of the given device whose
147   Add a request to the device's PM QoS list of resume latency constraints and
153   PM QoS list of resume latency constraints and remove sysfs attribute
157   Add a request to the device's PM QoS list of flags and create sysfs attribute
159   change the value of the PM_QOS_FLAG_NO_POWER_OFF flag.
163   list of flags and remove sysfs attribute pm_qos_no_power_off from the device's
168 The per-device PM QoS framework has a per-device notification tree.
174   The callback is called when the aggregated value of the device constraints
185 to energy-saving operation modes on the fly.  In those systems, if the operation
198 be passed to it.  If that value is negative, which means that the list of