836aedb141
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>
20 lines
877 B
Text
20 lines
877 B
Text
What: /sys/devices/.../power_state
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Date: January 2013
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Contact: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Description:
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The /sys/devices/.../power_state attribute is only present for
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device objects representing ACPI device nodes that provide power
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management methods.
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If present, it contains a string representing the current ACPI
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power state of the given device node. Its possible values,
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"D0", "D1", "D2", "D3hot", and "D3cold", reflect the power state
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names defined by the ACPI specification (ACPI 4 and above).
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If the device node uses shared ACPI power resources, this state
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determines a list of power resources required not to be turned
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off. However, some power resources needed by the device node in
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higher-power (lower-number) states may also be ON because of
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some other devices using them at the moment.
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This attribute is read-only.
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