Documentation/ABI/testing/sysfs-devices-power

Source file repositories/reference/linux-study-clean/Documentation/ABI/testing/sysfs-devices-power

File Facts

System
Linux kernel
Corpus path
Documentation/ABI/testing/sysfs-devices-power
Extension
[no extension]
Size
12863 bytes
Lines
308
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: Documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

What:		/sys/devices/.../power/
Date:		January 2009
Contact:	Rafael J. Wysocki <rafael@kernel.org>
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 <rafael@kernel.org>
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 <rafael@kernel.org>
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 <rafael@kernel.org>
Description:
		The /sys/devices/.../async attribute allows the user space to
		enable or disable 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

Annotation

Implementation Notes