mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 10:49:33 +00:00
![Rafael J. Wysocki](/assets/img/avatar_default.png)
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>
23 lines
1 KiB
Text
23 lines
1 KiB
Text
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.
|