xref: /linux/Documentation/ABI/testing/sysfs-devices-real_power_state (revision e5451c8f8330e03ad3cfa16048b4daf961af434f)
1*836aedb1SRafael J. WysockiWhat:		/sys/devices/.../real_power_state
2*836aedb1SRafael J. WysockiDate:		January 2013
3*836aedb1SRafael J. WysockiContact:	Rafael J. Wysocki <rafael.j.wysocki@intel.com>
4*836aedb1SRafael J. WysockiDescription:
5*836aedb1SRafael J. Wysocki		The /sys/devices/.../real_power_state attribute is only present
6*836aedb1SRafael J. Wysocki		for device objects representing ACPI device nodes that provide
7*836aedb1SRafael J. Wysocki		power management methods and use ACPI power resources for power
8*836aedb1SRafael J. Wysocki		management.
9*836aedb1SRafael J. Wysocki
10*836aedb1SRafael J. Wysocki		If present, it contains a string representing the real ACPI
11*836aedb1SRafael J. Wysocki		power state of the given device node as returned by the _PSC
12*836aedb1SRafael J. Wysocki		control method or inferred from the configuration of power
13*836aedb1SRafael J. Wysocki		resources.  Its possible values, "D0", "D1", "D2", "D3hot", and
14*836aedb1SRafael J. Wysocki		"D3cold", reflect the power state names defined by the ACPI
15*836aedb1SRafael J. Wysocki		specification (ACPI 4 and above).
16*836aedb1SRafael J. Wysocki
17*836aedb1SRafael J. Wysocki		In some situations the value of this attribute may be different
18*836aedb1SRafael J. Wysocki		from the value of the /sys/devices/.../power_state attribute for
19*836aedb1SRafael J. Wysocki		the same device object.  If that happens, some shared power
20*836aedb1SRafael J. Wysocki		resources used by the device node are only ON because of some
21*836aedb1SRafael J. Wysocki		other devices using them at the moment.
22*836aedb1SRafael J. Wysocki
23*836aedb1SRafael J. Wysocki		This attribute is read-only.
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