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+What: /sys/devices/.../power/
+Date: January 2009
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../power directory contains attributes
+ allowing the user space to check and modify some power
+ management related properties of given device.
+
+What: /sys/devices/.../power/wakeup
+Date: January 2009
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../power/wakeup attribute allows the user
+ space to check if the device is enabled to wake up the system
+ from sleep states, such as the memory sleep state (suspend to
+ RAM) and hibernation (suspend to disk), and to enable or disable
+ it to do that as desired.
+
+ Some devices support "wakeup" events, which are hardware signals
+ used to activate the system from a sleep state. Such devices
+ have one of the following two values for the sysfs power/wakeup
+ file:
+
+ + "enabled\n" to issue the events;
+ + "disabled\n" not to do so;
+
+ In that cases the user space can change the setting represented
+ by the contents of this file by writing either "enabled", or
+ "disabled" to it.
+
+ For the devices that are not capable of generating system wakeup
+ events this file is not present. In that case the device cannot
+ be enabled to wake up the system from sleep states.
+
+What: /sys/devices/.../power/control
+Date: January 2009
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../power/control attribute allows the user
+ space to control the run-time power management of the device.
+
+ All devices have one of the following two values for the
+ power/control file:
+
+ + "auto\n" to allow the device to be power managed at run time;
+ + "on\n" to prevent the device from being power managed;
+
+ The default for all devices is "auto", which means that they may
+ be subject to automatic power management, depending on their
+ drivers. Changing this attribute to "on" prevents the driver
+ from power managing the device at run time. Doing that while
+ the device is suspended causes it to be woken up.
+
+What: /sys/devices/.../power/async
+Date: January 2009
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../async attribute allows the user space to
+ enable or diasble the device's suspend and resume callbacks to
+ be executed asynchronously (ie. in separate threads, in parallel
+ with the main suspend/resume thread) during system-wide power
+ transitions (eg. suspend to RAM, hibernation).
+
+ All devices have one of the following two values for the
+ power/async file:
+
+ + "enabled\n" to permit the asynchronous suspend/resume;
+ + "disabled\n" to forbid it;
+
+ The value of this attribute may be changed by writing either
+ "enabled", or "disabled" to it.
+
+ It generally is unsafe to permit the asynchronous suspend/resume
+ of a device unless it is certain that all of the PM dependencies
+ of the device are known to the PM core. However, for some
+ devices this attribute is set to "enabled" by bus type code or
+ device drivers and in that cases it should be safe to leave the
+ default value.
+
+What: /sys/devices/.../power/wakeup_count
+Date: September 2010
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../wakeup_count attribute contains the number
+ of signaled wakeup events associated with the device. This
+ attribute is read-only. If the device is not enabled to wake up
+ the system from sleep states, this attribute is not present.
+
+What: /sys/devices/.../power/wakeup_active_count
+Date: September 2010
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../wakeup_active_count attribute contains the
+ number of times the processing of wakeup events associated with
+ the device was completed (at the kernel level). This attribute
+ is read-only. If the device is not enabled to wake up the
+ system from sleep states, this attribute is not present.
+
+What: /sys/devices/.../power/wakeup_abort_count
+Date: February 2012
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../wakeup_abort_count attribute contains the
+ number of times the processing of a wakeup event associated with
+ the device might have aborted system transition into a sleep
+ state in progress. This attribute is read-only. If the device
+ is not enabled to wake up the system from sleep states, this
+ attribute is not present.
+
+What: /sys/devices/.../power/wakeup_expire_count
+Date: February 2012
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../wakeup_expire_count attribute contains the
+ number of times a wakeup event associated with the device has
+ been reported with a timeout that expired. This attribute is
+ read-only. If the device is not enabled to wake up the system
+ from sleep states, this attribute is not present.
+
+What: /sys/devices/.../power/wakeup_active
+Date: September 2010
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../wakeup_active attribute contains either 1,
+ or 0, depending on whether or not a wakeup event associated with
+ the device is being processed (1). This attribute is read-only.
+ If the device is not enabled to wake up the system from sleep
+ states, this attribute is not present.
+
+What: /sys/devices/.../power/wakeup_total_time_ms
+Date: September 2010
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../wakeup_total_time_ms attribute contains
+ the total time of processing wakeup events associated with the
+ device, in milliseconds. This attribute is read-only. If the
+ device is not enabled to wake up the system from sleep states,
+ this attribute is not present.
+
+What: /sys/devices/.../power/wakeup_max_time_ms
+Date: September 2010
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../wakeup_max_time_ms attribute contains
+ the maximum time of processing a single wakeup event associated
+ with the device, in milliseconds. This attribute is read-only.
+ If the device is not enabled to wake up the system from sleep
+ states, this attribute is not present.
+
+What: /sys/devices/.../power/wakeup_last_time_ms
+Date: September 2010
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../wakeup_last_time_ms attribute contains
+ the value of the monotonic clock corresponding to the time of
+ signaling the last wakeup event associated with the device, in
+ milliseconds. This attribute is read-only. If the device is
+ not enabled to wake up the system from sleep states, this
+ attribute is not present.
+
+What: /sys/devices/.../power/wakeup_prevent_sleep_time_ms
+Date: February 2012
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../wakeup_prevent_sleep_time_ms attribute
+ contains the total time the device has been preventing
+ opportunistic transitions to sleep states from occurring.
+ This attribute is read-only. If the device is not enabled to
+ wake up the system from sleep states, this attribute is not
+ present.
+
+What: /sys/devices/.../power/autosuspend_delay_ms
+Date: September 2010
+Contact: Alan Stern <stern@rowland.harvard.edu>
+Description:
+ The /sys/devices/.../power/autosuspend_delay_ms attribute
+ contains the autosuspend delay value (in milliseconds). Some
+ drivers do not want their device to suspend as soon as it
+ becomes idle at run time; they want the device to remain
+ inactive for a certain minimum period of time first. That
+ period is called the autosuspend delay. Negative values will
+ prevent the device from being suspended at run time (similar
+ to writing "on" to the power/control attribute). Values >=
+ 1000 will cause the autosuspend timer expiration to be rounded
+ up to the nearest second.
+
+ Not all drivers support this attribute. If it isn't supported,
+ attempts to read or write it will yield I/O errors.
+
+What: /sys/devices/.../power/pm_qos_latency_us
+Date: March 2012
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../power/pm_qos_resume_latency_us attribute
+ contains the PM QoS resume latency limit for the given device,
+ which is the maximum allowed time it can take to resume the
+ device, after it has been suspended at run time, from a resume
+ request to the moment the device will be ready to process I/O,
+ in microseconds. If it is equal to 0, however, this means that
+ the PM QoS resume latency may be arbitrary.
+
+ Not all drivers support this attribute. If it isn't supported,
+ it is not present.
+
+ This attribute has no effect on system-wide suspend/resume and
+ hibernation.
+
+What: /sys/devices/.../power/pm_qos_no_power_off
+Date: September 2012
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../power/pm_qos_no_power_off attribute
+ is used for manipulating the PM QoS "no power off" flag. If
+ set, this flag indicates to the kernel that power should not
+ be removed entirely from the device.
+
+ Not all drivers support this attribute. If it isn't supported,
+ it is not present.
+
+ This attribute has no effect on system-wide suspend/resume and
+ hibernation.
+
+What: /sys/devices/.../power/pm_qos_remote_wakeup
+Date: September 2012
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../power/pm_qos_remote_wakeup attribute
+ is used for manipulating the PM QoS "remote wakeup required"
+ flag. If set, this flag indicates to the kernel that the
+ device is a source of user events that have to be signaled from
+ its low-power states.
+
+ Not all drivers support this attribute. If it isn't supported,
+ it is not present.
+
+ This attribute has no effect on system-wide suspend/resume and
+ hibernation.