| 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. |