diff options
| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-01-24 12:49:59 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-01-24 12:49:59 +0100 |
| commit | 836aedb1414d4724b2ec68dd19810960c593720c (patch) | |
| tree | 4f826283e16638ba521f5d31b021d79166cfde99 /Documentation/ABI/testing/sysfs-devices-real_power_state | |
| parent | cf860be639d86ed77af179c925085ae0721ae602 (diff) | |
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>
Diffstat (limited to 'Documentation/ABI/testing/sysfs-devices-real_power_state')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-devices-real_power_state | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-real_power_state b/Documentation/ABI/testing/sysfs-devices-real_power_state new file mode 100644 index 000000000000..8b3527c82a7d --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices-real_power_state @@ -0,0 +1,23 @@ +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. |