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authorRafael J. Wysocki <rjw@sisk.pl>2010-01-23 22:03:22 +0100
committerRafael J. Wysocki <rjw@sisk.pl>2010-02-26 20:39:09 +0100
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PM: Document device power attributes in sysfs
There are sysfs attributes in /sys/devices/.../power/ that haven't been documented yet in Documentation/ABI/. Document them as appropriate. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
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+What: /sys/devices/.../power/
+Date: January 2009
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../power directory contains attributes
+ allowing the user space to check and modify some power
+ management related properties of given device.
+
+What: /sys/devices/.../power/wakeup
+Date: January 2009
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../power/wakeup attribute allows the user
+ space to check if the device is enabled to wake up the system
+ from sleep states, such as the memory sleep state (suspend to
+ RAM) and hibernation (suspend to disk), and to enable or disable
+ it to do that as desired.
+
+ Some devices support "wakeup" events, which are hardware signals
+ used to activate the system from a sleep state. Such devices
+ have one of the following two values for the sysfs power/wakeup
+ file:
+
+ + "enabled\n" to issue the events;
+ + "disabled\n" not to do so;
+
+ In that cases the user space can change the setting represented
+ by the contents of this file by writing either "enabled", or
+ "disabled" to it.
+
+ For the devices that are not capable of generating system wakeup
+ events this file contains "\n". In that cases the user space
+ cannot modify the contents of this file and the device cannot be
+ enabled to wake up the system.
+
+What: /sys/devices/.../power/control
+Date: January 2009
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/devices/.../power/control attribute allows the user
+ space to control the run-time power management of the device.
+
+ All devices have one of the following two values for the
+ power/control file:
+
+ + "auto\n" to allow the device to be power managed at run time;
+ + "on\n" to prevent the device from being power managed;
+
+ The default for all devices is "auto", which means that they may
+ be subject to automatic power management, depending on their
+ drivers. Changing this attribute to "on" prevents the driver
+ from power managing the device at run time. Doing that while
+ the device is suspended causes it to be woken up.