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lf-6.6.y
linux-imx/Documentation/ABI/testing/sysfs-devices-real_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/.../real_power_state Date: January 2013 Contact: Rafael J. Wysocki rafael.j.wysocki@intel.com Description: The /sys/devices/.../real_power_state attribute is only present for device objects representing ACPI device nodes that provide power management methods and use ACPI power resources for power management.

	If present, it contains a string representing the real ACPI
	power state of the given device node as returned by the _PSC
	control method or inferred from the configuration of power
	resources.  Its possible values, "D0", "D1", "D2", "D3hot", and
	"D3cold", reflect the power state names defined by the ACPI
	specification (ACPI 4 and above).

	In some situations the value of this attribute may be different
	from the value of the /sys/devices/.../power_state attribute for
	the same device object.  If that happens, some shared power
	resources used by the device node are only ON because of some
	other devices using them at the moment.

	This attribute is read-only.