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linux-imx/Documentation/ABI/testing/sysfs-devices-power_state
Rafael J. Wysocki 836aedb141 ACPI / PM: Expose power states of ACPI devices to user space 
Make it possible to retrieve the current power state of a device with
ACPI power management from user space via sysfs by adding two new
attributes, power_state and real_power_state, to the sysfs directory
associated with the struct acpi_device object representing the
device's ACPI node.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-24 12:49:59 +01:00

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What: /sys/devices/.../power_state Date: January 2013 Contact: Rafael J. Wysocki rafael.j.wysocki@intel.com Description: The /sys/devices/.../power_state attribute is only present for device objects representing ACPI device nodes that provide power management methods.

	If present, it contains a string representing the current ACPI
	power state of the given device node.  Its possible values,
	"D0", "D1", "D2", "D3hot", and "D3cold", reflect the power state
	names defined by the ACPI specification (ACPI 4 and above).

	If the device node uses shared ACPI power resources, this state
	determines a list of power resources required not to be turned
	off.  However, some power resources needed by the device node in
	higher-power (lower-number) states may also be ON because of
	some other devices using them at the moment.

	This attribute is read-only.