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Based on kernel version 3.15.4. Page generated on 2014-07-07 08:59 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 capable to wake up
87			the system from sleep states, this attribute is not present.
88			If the device is not enabled to wake up the system from sleep
89			states, this attribute is empty.
90	
91	What:		/sys/devices/.../power/wakeup_active_count
92	Date:		September 2010
93	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
94	Description:
95			The /sys/devices/.../wakeup_active_count attribute contains the
96			number of times the processing of wakeup events associated with
97			the device was completed (at the kernel level).  This attribute
98			is read-only.  If the device is not capable to wake up the
99			system from sleep states, this attribute is not present.  If
100			the device is not enabled to wake up the system from sleep
101			states, this attribute is empty.
102	
103	What:		/sys/devices/.../power/wakeup_abort_count
104	Date:		February 2012
105	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
106	Description:
107			The /sys/devices/.../wakeup_abort_count attribute contains the
108			number of times the processing of a wakeup event associated with
109			the device might have aborted system transition into a sleep
110			state in progress.  This attribute is read-only.  If the device
111			is not capable to wake up the system from sleep states, this
112			attribute is not present.  If the device is not enabled to wake
113			up the system from sleep states, this attribute is empty.
114	
115	What:		/sys/devices/.../power/wakeup_expire_count
116	Date:		February 2012
117	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
118	Description:
119			The /sys/devices/.../wakeup_expire_count attribute contains the
120			number of times a wakeup event associated with the device has
121			been reported with a timeout that expired.  This attribute is
122			read-only.  If the device is not capable to wake up the system
123			from sleep states, this attribute is not present.  If the
124			device is not enabled to wake up the system from sleep states,
125			this attribute is empty.
126	
127	What:		/sys/devices/.../power/wakeup_active
128	Date:		September 2010
129	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
130	Description:
131			The /sys/devices/.../wakeup_active attribute contains either 1,
132			or 0, depending on whether or not a wakeup event associated with
133			the device is being processed (1).  This attribute is read-only.
134			If the device is not capable to wake up the system from sleep
135			states, this attribute is not present.  If the device is not
136			enabled to wake up the system from sleep states, this attribute
137			is empty.
138	
139	What:		/sys/devices/.../power/wakeup_total_time_ms
140	Date:		September 2010
141	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
142	Description:
143			The /sys/devices/.../wakeup_total_time_ms attribute contains
144			the total time of processing wakeup events associated with the
145			device, in milliseconds.  This attribute is read-only.  If the
146			device is not capable to wake up the system from sleep states,
147			this attribute is not present.  If the device is not enabled to
148			wake up the system from sleep states, this attribute is empty.
149	
150	What:		/sys/devices/.../power/wakeup_max_time_ms
151	Date:		September 2010
152	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
153	Description:
154			The /sys/devices/.../wakeup_max_time_ms attribute contains
155			the maximum time of processing a single wakeup event associated
156			with the device, in milliseconds.  This attribute is read-only.
157			If the device is not capable to wake up the system from sleep
158			states, this attribute is not present.  If the device is not
159			enabled to wake up the system from sleep states, this attribute
160			is empty.
161	
162	What:		/sys/devices/.../power/wakeup_last_time_ms
163	Date:		September 2010
164	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
165	Description:
166			The /sys/devices/.../wakeup_last_time_ms attribute contains
167			the value of the monotonic clock corresponding to the time of
168			signaling the last wakeup event associated with the device, in
169			milliseconds.  This attribute is read-only.  If the device is
170			not enabled to wake up the system from sleep states, this
171			attribute is not present.  If the device is not enabled to wake
172			up the system from sleep states, this attribute is empty.
173	
174	What:		/sys/devices/.../power/wakeup_prevent_sleep_time_ms
175	Date:		February 2012
176	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
177	Description:
178			The /sys/devices/.../wakeup_prevent_sleep_time_ms attribute
179			contains the total time the device has been preventing
180			opportunistic transitions to sleep states from occurring.
181			This attribute is read-only.  If the device is not capable to
182			wake up the system from sleep states, this attribute is not
183			present.  If the device is not enabled to wake up the system
184			from sleep states, this attribute is empty.
185	
186	What:		/sys/devices/.../power/autosuspend_delay_ms
187	Date:		September 2010
188	Contact:	Alan Stern <stern@rowland.harvard.edu>
189	Description:
190			The /sys/devices/.../power/autosuspend_delay_ms attribute
191			contains the autosuspend delay value (in milliseconds).  Some
192			drivers do not want their device to suspend as soon as it
193			becomes idle at run time; they want the device to remain
194			inactive for a certain minimum period of time first.  That
195			period is called the autosuspend delay.  Negative values will
196			prevent the device from being suspended at run time (similar
197			to writing "on" to the power/control attribute).  Values >=
198			1000 will cause the autosuspend timer expiration to be rounded
199			up to the nearest second.
200	
201			Not all drivers support this attribute.  If it isn't supported,
202			attempts to read or write it will yield I/O errors.
203	
204	What:		/sys/devices/.../power/pm_qos_resume_latency_us
205	Date:		March 2012
206	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
207	Description:
208			The /sys/devices/.../power/pm_qos_resume_latency_us attribute
209			contains the PM QoS resume latency limit for the given device,
210			which is the maximum allowed time it can take to resume the
211			device, after it has been suspended at run time, from a resume
212			request to the moment the device will be ready to process I/O,
213			in microseconds.  If it is equal to 0, however, this means that
214			the PM QoS resume latency may be arbitrary.
215	
216			Not all drivers support this attribute.  If it isn't supported,
217			it is not present.
218	
219			This attribute has no effect on system-wide suspend/resume and
220			hibernation.
221	
222	What:		/sys/devices/.../power/pm_qos_latency_tolerance_us
223	Date:		January 2014
224	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
225	Description:
226			The /sys/devices/.../power/pm_qos_latency_tolerance_us attribute
227			contains the PM QoS active state latency tolerance limit for the
228			given device in microseconds.  That is the maximum memory access
229			latency the device can suffer without any visible adverse
230			effects on user space functionality.  If that value is the
231			string "any", the latency does not matter to user space at all,
232			but hardware should not be allowed to set the latency tolerance
233			for the device automatically.
234	
235			Reading "auto" from this file means that the maximum memory
236			access latency for the device may be determined automatically
237			by the hardware as needed.  Writing "auto" to it allows the
238			hardware to be switched to this mode if there are no other
239			latency tolerance requirements from the kernel side.
240	
241			This attribute is only present if the feature controlled by it
242			is supported by the hardware.
243	
244			This attribute has no effect on runtime suspend and resume of
245			devices and on system-wide suspend/resume and hibernation.
246	
247	What:		/sys/devices/.../power/pm_qos_no_power_off
248	Date:		September 2012
249	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
250	Description:
251			The /sys/devices/.../power/pm_qos_no_power_off attribute
252			is used for manipulating the PM QoS "no power off" flag.  If
253			set, this flag indicates to the kernel that power should not
254			be removed entirely from the device.
255	
256			Not all drivers support this attribute.  If it isn't supported,
257			it is not present.
258	
259			This attribute has no effect on system-wide suspend/resume and
260			hibernation.
261	
262	What:		/sys/devices/.../power/pm_qos_remote_wakeup
263	Date:		September 2012
264	Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
265	Description:
266			The /sys/devices/.../power/pm_qos_remote_wakeup attribute
267			is used for manipulating the PM QoS "remote wakeup required"
268			flag.  If set, this flag indicates to the kernel that the
269			device is a source of user events that have to be signaled from
270			its low-power states.
271	
272			Not all drivers support this attribute.  If it isn't supported,
273			it is not present.
274	
275			This attribute has no effect on system-wide suspend/resume and
276			hibernation.
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