xref: /linux/Documentation/ABI/testing/sysfs-devices-real_power_state (revision 71e2f4dd5a65bd8dbca0b77661e75eea471168f8)
1What:		/sys/devices/.../real_power_state
2Date:		January 2013
3Contact:	Rafael J. Wysocki <rafael.j.wysocki@intel.com>
4Description:
5		The /sys/devices/.../real_power_state attribute is only present
6		for device objects representing ACPI device nodes that provide
7		power management methods and use ACPI power resources for power
8		management.
9
10		If present, it contains a string representing the real ACPI
11		power state of the given device node as returned by the _PSC
12		control method or inferred from the configuration of power
13		resources.  Its possible values, "D0", "D1", "D2", "D3hot", and
14		"D3cold", reflect the power state names defined by the ACPI
15		specification (ACPI 4 and above).
16
17		In some situations the value of this attribute may be different
18		from the value of the /sys/devices/.../power_state attribute for
19		the same device object.  If that happens, some shared power
20		resources used by the device node are only ON because of some
21		other devices using them at the moment.
22
23		This attribute is read-only.
24