linux/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

24 lines
1.0 KiB
Plaintext

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.