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Based on kernel version 3.13. Page generated on 2014-01-20 21:59 EST.

1	What:		/sys/devices/.../power/
2	Date:		January 2009
3	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
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@rjwysocki.net>
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@rjwysocki.net>
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@rjwysocki.net>
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@rjwysocki.net>
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@rjwysocki.net>
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_abort_count
100	Date:		February 2012
101	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
102	Description:
103			The /sys/devices/.../wakeup_abort_count attribute contains the
104			number of times the processing of a wakeup event associated with
105			the device might have aborted system transition into a sleep
106			state in progress.  This attribute is read-only.  If the device
107			is not enabled to wake up the system from sleep states, this
108			attribute is not present.
109	
110	What:		/sys/devices/.../power/wakeup_expire_count
111	Date:		February 2012
112	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
113	Description:
114			The /sys/devices/.../wakeup_expire_count attribute contains the
115			number of times a wakeup event associated with the device has
116			been reported with a timeout that expired.  This attribute is
117			read-only.  If the device is not enabled to wake up the system
118			from sleep states, this attribute is not present.
119	
120	What:		/sys/devices/.../power/wakeup_active
121	Date:		September 2010
122	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
123	Description:
124			The /sys/devices/.../wakeup_active attribute contains either 1,
125			or 0, depending on whether or not a wakeup event associated with
126			the device is being processed (1).  This attribute is read-only.
127			If the device is not enabled to wake up the system from sleep
128			states, this attribute is not present.
129	
130	What:		/sys/devices/.../power/wakeup_total_time_ms
131	Date:		September 2010
132	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
133	Description:
134			The /sys/devices/.../wakeup_total_time_ms attribute contains
135			the total time of processing wakeup events associated with the
136			device, in milliseconds.  This attribute is read-only.  If the
137			device is not enabled to wake up the system from sleep states,
138			this attribute is not present.
139	
140	What:		/sys/devices/.../power/wakeup_max_time_ms
141	Date:		September 2010
142	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
143	Description:
144			The /sys/devices/.../wakeup_max_time_ms attribute contains
145			the maximum time of processing a single wakeup event associated
146			with the device, in milliseconds.  This attribute is read-only.
147			If the device is not enabled to wake up the system from sleep
148			states, this attribute is not present.
149	
150	What:		/sys/devices/.../power/wakeup_last_time_ms
151	Date:		September 2010
152	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
153	Description:
154			The /sys/devices/.../wakeup_last_time_ms attribute contains
155			the value of the monotonic clock corresponding to the time of
156			signaling the last wakeup event associated with the device, in
157			milliseconds.  This attribute is read-only.  If the device is
158			not enabled to wake up the system from sleep states, this
159			attribute is not present.
160	
161	What:		/sys/devices/.../power/wakeup_prevent_sleep_time_ms
162	Date:		February 2012
163	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
164	Description:
165			The /sys/devices/.../wakeup_prevent_sleep_time_ms attribute
166			contains the total time the device has been preventing
167			opportunistic transitions to sleep states from occurring.
168			This attribute is read-only.  If the device is not enabled to
169			wake up the system from sleep states, this attribute is not
170			present.
171	
172	What:		/sys/devices/.../power/autosuspend_delay_ms
173	Date:		September 2010
174	Contact:	Alan Stern <stern@rowland.harvard.edu>
175	Description:
176			The /sys/devices/.../power/autosuspend_delay_ms attribute
177			contains the autosuspend delay value (in milliseconds).  Some
178			drivers do not want their device to suspend as soon as it
179			becomes idle at run time; they want the device to remain
180			inactive for a certain minimum period of time first.  That
181			period is called the autosuspend delay.  Negative values will
182			prevent the device from being suspended at run time (similar
183			to writing "on" to the power/control attribute).  Values >=
184			1000 will cause the autosuspend timer expiration to be rounded
185			up to the nearest second.
186	
187			Not all drivers support this attribute.  If it isn't supported,
188			attempts to read or write it will yield I/O errors.
189	
190	What:		/sys/devices/.../power/pm_qos_latency_us
191	Date:		March 2012
192	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
193	Description:
194			The /sys/devices/.../power/pm_qos_resume_latency_us attribute
195			contains the PM QoS resume latency limit for the given device,
196			which is the maximum allowed time it can take to resume the
197			device, after it has been suspended at run time, from a resume
198			request to the moment the device will be ready to process I/O,
199			in microseconds.  If it is equal to 0, however, this means that
200			the PM QoS resume latency may be arbitrary.
201	
202			Not all drivers support this attribute.  If it isn't supported,
203			it is not present.
204	
205			This attribute has no effect on system-wide suspend/resume and
206			hibernation.
207	
208	What:		/sys/devices/.../power/pm_qos_no_power_off
209	Date:		September 2012
210	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
211	Description:
212			The /sys/devices/.../power/pm_qos_no_power_off attribute
213			is used for manipulating the PM QoS "no power off" flag.  If
214			set, this flag indicates to the kernel that power should not
215			be removed entirely from the device.
216	
217			Not all drivers support this attribute.  If it isn't supported,
218			it is not present.
219	
220			This attribute has no effect on system-wide suspend/resume and
221			hibernation.
222	
223	What:		/sys/devices/.../power/pm_qos_remote_wakeup
224	Date:		September 2012
225	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
226	Description:
227			The /sys/devices/.../power/pm_qos_remote_wakeup attribute
228			is used for manipulating the PM QoS "remote wakeup required"
229			flag.  If set, this flag indicates to the kernel that the
230			device is a source of user events that have to be signaled from
231			its low-power states.
232	
233			Not all drivers support this attribute.  If it isn't supported,
234			it is not present.
235	
236			This attribute has no effect on system-wide suspend/resume and
237			hibernation.
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