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.