Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 971cb7fb authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

PM: Document device power attributes in sysfs 



There are sysfs attributes in /sys/devices/.../power/ that haven't
been documented yet in Documentation/ABI/.  Document them as
appropriate.

Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
parent 53823639

Documentation/ABI/testing/sysfs-devices-power

0 → 100644
+53 −0
Original line number Diff line number Diff line 
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 contains "\n".  In that cases the user space

		cannot modify the contents of this file and the device cannot be

		enabled to wake up the system.



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.