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Based on kernel version 3.3. Page generated on 2012-03-23 21:23 EST.

1	What:		/sys/devices/.../power/
2	Date:		January 2009
3	Contact:	Rafael J. Wysocki <rjw@sisk.pl>
4	Description:
5			The /sys/devices/.../power directory contains attributes
6			allowing the user space to check and modify some power
7			management related properties of given device.
8	
9	What:		/sys/devices/.../power/wakeup
10	Date:		January 2009
11	Contact:	Rafael J. Wysocki <rjw@sisk.pl>
12	Description:
13			The /sys/devices/.../power/wakeup attribute allows the user
14			space to check if the device is enabled to wake up the system
15			from sleep states, such as the memory sleep state (suspend to
16			RAM) and hibernation (suspend to disk), and to enable or disable
17			it to do that as desired.
18	
19			Some devices support "wakeup" events, which are hardware signals
20			used to activate the system from a sleep state.  Such devices
21			have one of the following two values for the sysfs power/wakeup
22			file:
23	
24			+ "enabled\n" to issue the events;
25			+ "disabled\n" not to do so;
26	
27			In that cases the user space can change the setting represented
28			by the contents of this file by writing either "enabled", or
29			"disabled" to it.
30	
31			For the devices that are not capable of generating system wakeup
32			events this file is not present.  In that case the device cannot
33			be enabled to wake up the system from sleep states.
34	
35	What:		/sys/devices/.../power/control
36	Date:		January 2009
37	Contact:	Rafael J. Wysocki <rjw@sisk.pl>
38	Description:
39			The /sys/devices/.../power/control attribute allows the user
40			space to control the run-time power management of the device.
41	
42			All devices have one of the following two values for the
43			power/control file:
44	
45			+ "auto\n" to allow the device to be power managed at run time;
46			+ "on\n" to prevent the device from being power managed;
47	
48			The default for all devices is "auto", which means that they may
49			be subject to automatic power management, depending on their
50			drivers.  Changing this attribute to "on" prevents the driver
51			from power managing the device at run time.  Doing that while
52			the device is suspended causes it to be woken up.
53	
54	What:		/sys/devices/.../power/async
55	Date:		January 2009
56	Contact:	Rafael J. Wysocki <rjw@sisk.pl>
57	Description:
58			The /sys/devices/.../async attribute allows the user space to
59			enable or diasble the device's suspend and resume callbacks to
60			be executed asynchronously (ie. in separate threads, in parallel
61			with the main suspend/resume thread) during system-wide power
62			transitions (eg. suspend to RAM, hibernation).
63	
64			All devices have one of the following two values for the
65			power/async file:
66	
67			+ "enabled\n" to permit the asynchronous suspend/resume;
68			+ "disabled\n" to forbid it;
69	
70			The value of this attribute may be changed by writing either
71			"enabled", or "disabled" to it.
72	
73			It generally is unsafe to permit the asynchronous suspend/resume
74			of a device unless it is certain that all of the PM dependencies
75			of the device are known to the PM core.  However, for some
76			devices this attribute is set to "enabled" by bus type code or
77			device drivers and in that cases it should be safe to leave the
78			default value.
79	
80	What:		/sys/devices/.../power/wakeup_count
81	Date:		September 2010
82	Contact:	Rafael J. Wysocki <rjw@sisk.pl>
83	Description:
84			The /sys/devices/.../wakeup_count attribute contains the number
85			of signaled wakeup events associated with the device.  This
86			attribute is read-only.  If the device is not enabled to wake up
87			the system from sleep states, this attribute is not present.
88	
89	What:		/sys/devices/.../power/wakeup_active_count
90	Date:		September 2010
91	Contact:	Rafael J. Wysocki <rjw@sisk.pl>
92	Description:
93			The /sys/devices/.../wakeup_active_count attribute contains the
94			number of times the processing of wakeup events associated with
95			the device was completed (at the kernel level).  This attribute
96			is read-only.  If the device is not enabled to wake up the
97			system from sleep states, this attribute is not present.
98	
99	What:		/sys/devices/.../power/wakeup_hit_count
100	Date:		September 2010
101	Contact:	Rafael J. Wysocki <rjw@sisk.pl>
102	Description:
103			The /sys/devices/.../wakeup_hit_count attribute contains the
104			number of times the processing of a wakeup event associated with
105			the device might prevent the system from entering a sleep state.
106			This attribute is read-only.  If the device is not enabled to
107			wake up the system from sleep states, this attribute is not
108			present.
109	
110	What:		/sys/devices/.../power/wakeup_active
111	Date:		September 2010
112	Contact:	Rafael J. Wysocki <rjw@sisk.pl>
113	Description:
114			The /sys/devices/.../wakeup_active attribute contains either 1,
115			or 0, depending on whether or not a wakeup event associated with
116			the device is being processed (1).  This attribute is read-only.
117			If the device is not enabled to wake up the system from sleep
118			states, this attribute is not present.
119	
120	What:		/sys/devices/.../power/wakeup_total_time_ms
121	Date:		September 2010
122	Contact:	Rafael J. Wysocki <rjw@sisk.pl>
123	Description:
124			The /sys/devices/.../wakeup_total_time_ms attribute contains
125			the total time of processing wakeup events associated with the
126			device, in milliseconds.  This attribute is read-only.  If the
127			device is not enabled to wake up the system from sleep states,
128			this attribute is not present.
129	
130	What:		/sys/devices/.../power/wakeup_max_time_ms
131	Date:		September 2010
132	Contact:	Rafael J. Wysocki <rjw@sisk.pl>
133	Description:
134			The /sys/devices/.../wakeup_max_time_ms attribute contains
135			the maximum time of processing a single wakeup event associated
136			with the device, in milliseconds.  This attribute is read-only.
137			If the device is not enabled to wake up the system from sleep
138			states, this attribute is not present.
139	
140	What:		/sys/devices/.../power/wakeup_last_time_ms
141	Date:		September 2010
142	Contact:	Rafael J. Wysocki <rjw@sisk.pl>
143	Description:
144			The /sys/devices/.../wakeup_last_time_ms attribute contains
145			the value of the monotonic clock corresponding to the time of
146			signaling the last wakeup event associated with the device, in
147			milliseconds.  This attribute is read-only.  If the device is
148			not enabled to wake up the system from sleep states, this
149			attribute is not present.
150	
151	What:		/sys/devices/.../power/autosuspend_delay_ms
152	Date:		September 2010
153	Contact:	Alan Stern <stern@rowland.harvard.edu>
154	Description:
155			The /sys/devices/.../power/autosuspend_delay_ms attribute
156			contains the autosuspend delay value (in milliseconds).  Some
157			drivers do not want their device to suspend as soon as it
158			becomes idle at run time; they want the device to remain
159			inactive for a certain minimum period of time first.  That
160			period is called the autosuspend delay.  Negative values will
161			prevent the device from being suspended at run time (similar
162			to writing "on" to the power/control attribute).  Values >=
163			1000 will cause the autosuspend timer expiration to be rounded
164			up to the nearest second.
165	
166			Not all drivers support this attribute.  If it isn't supported,
167			attempts to read or write it will yield I/O errors.
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