What: /sys/devices/.../power/ Date: January 2009 Contact: Rafael J. Wysocki 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 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 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 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 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 capable to wake up the system from sleep states, this attribute is not present. If the device is not enabled to wake up the system from sleep states, this attribute is empty. What: /sys/devices/.../power/wakeup_active_count Date: September 2010 Contact: Rafael J. Wysocki 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 capable to wake up the system from sleep states, this attribute is not present. If the device is not enabled to wake up the system from sleep states, this attribute is empty. What: /sys/devices/.../power/wakeup_abort_count Date: February 2012 Contact: Rafael J. Wysocki 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 capable to wake up the system from sleep states, this attribute is not present. If the device is not enabled to wake up the system from sleep states, this attribute is empty. What: /sys/devices/.../power/wakeup_expire_count Date: February 2012 Contact: Rafael J. Wysocki 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 capable to wake up the system from sleep states, this attribute is not present. If the device is not enabled to wake up the system from sleep states, this attribute is empty. What: /sys/devices/.../power/wakeup_active Date: September 2010 Contact: Rafael J. Wysocki 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 capable to wake up the system from sleep states, this attribute is not present. If the device is not enabled to wake up the system from sleep states, this attribute is empty. What: /sys/devices/.../power/wakeup_total_time_ms Date: September 2010 Contact: Rafael J. Wysocki 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 capable to wake up the system from sleep states, this attribute is not present. If the device is not enabled to wake up the system from sleep states, this attribute is empty. What: /sys/devices/.../power/wakeup_max_time_ms Date: September 2010 Contact: Rafael J. Wysocki 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 capable to wake up the system from sleep states, this attribute is not present. If the device is not enabled to wake up the system from sleep states, this attribute is empty. What: /sys/devices/.../power/wakeup_last_time_ms Date: September 2010 Contact: Rafael J. Wysocki 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. If the device is not enabled to wake up the system from sleep states, this attribute is empty. What: /sys/devices/.../power/wakeup_prevent_sleep_time_ms Date: February 2012 Contact: Rafael J. Wysocki 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 capable to wake up the system from sleep states, this attribute is not present. If the device is not enabled to wake up the system from sleep states, this attribute is empty. What: /sys/devices/.../power/autosuspend_delay_ms Date: September 2010 Contact: Alan Stern 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_resume_latency_us Date: March 2012 Contact: Rafael J. Wysocki 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 and the special value "n/a" means that user space cannot accept any resume latency at all for the given 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_latency_tolerance_us Date: January 2014 Contact: Rafael J. Wysocki Description: The /sys/devices/.../power/pm_qos_latency_tolerance_us attribute contains the PM QoS active state latency tolerance limit for the given device in microseconds. That is the maximum memory access latency the device can suffer without any visible adverse effects on user space functionality. If that value is the string "any", the latency does not matter to user space at all, but hardware should not be allowed to set the latency tolerance for the device automatically. Reading "auto" from this file means that the maximum memory access latency for the device may be determined automatically by the hardware as needed. Writing "auto" to it allows the hardware to be switched to this mode if there are no other latency tolerance requirements from the kernel side. This attribute is only present if the feature controlled by it is supported by the hardware. This attribute has no effect on runtime suspend and resume of devices and on system-wide suspend/resume and hibernation. What: /sys/devices/.../power/pm_qos_no_power_off Date: September 2012 Contact: Rafael J. Wysocki 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/runtime_status Date: April 2010 Contact: Rafael J. Wysocki Description: The /sys/devices/.../power/runtime_status attribute contains the current runtime PM status of the device, which may be "suspended", "suspending", "resuming", "active", "error" (fatal error), or "unsupported" (runtime PM is disabled). What: /sys/devices/.../power/runtime_active_time Date: Jul 2010 Contact: Arjan van de Ven Description: Reports the total time that the device has been active. Used for runtime PM statistics. What: /sys/devices/.../power/runtime_suspended_time Date: Jul 2010 Contact: Arjan van de Ven Description: Reports total time that the device has been suspended. Used for runtime PM statistics. What: /sys/devices/.../power/runtime_usage Date: Apr 2010 Contact: Dominik Brodowski Description: Reports the runtime PM usage count of a device. What: /sys/devices/.../power/runtime_enabled Date: Apr 2010 Contact: Dominik Brodowski Description: Is runtime PM enabled for this device? States are "enabled", "disabled", "forbidden" or a combination of the latter two. What: /sys/devices/.../power/runtime_active_kids Date: Apr 2010 Contact: Dominik Brodowski Description: Reports the runtime PM children usage count of a device, or 0 if the children will be ignored.