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Rafael J. Wysocki971cb7f2010-01-23 22:03:22 +01001What: /sys/devices/.../power/
2Date: January 2009
3Contact: Rafael J. Wysocki <rjw@sisk.pl>
4Description:
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
9What: /sys/devices/.../power/wakeup
10Date: January 2009
11Contact: Rafael J. Wysocki <rjw@sisk.pl>
12Description:
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
Rafael J. Wysockicb8f51b2011-02-08 23:26:02 +010032 events this file is not present. In that case the device cannot
33 be enabled to wake up the system from sleep states.
Rafael J. Wysocki971cb7f2010-01-23 22:03:22 +010034
35What: /sys/devices/.../power/control
36Date: January 2009
37Contact: Rafael J. Wysocki <rjw@sisk.pl>
38Description:
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.
Rafael J. Wysocki5a2eb852010-01-23 22:25:23 +010053
54What: /sys/devices/.../power/async
55Date: January 2009
56Contact: Rafael J. Wysocki <rjw@sisk.pl>
57Description:
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.
Rafael J. Wysocki074037e2010-09-22 22:09:10 +020079
80What: /sys/devices/.../power/wakeup_count
81Date: September 2010
82Contact: Rafael J. Wysocki <rjw@sisk.pl>
83Description:
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
Rafael J. Wysockicb8f51b2011-02-08 23:26:02 +010087 the system from sleep states, this attribute is not present.
Rafael J. Wysocki074037e2010-09-22 22:09:10 +020088
89What: /sys/devices/.../power/wakeup_active_count
90Date: September 2010
91Contact: Rafael J. Wysocki <rjw@sisk.pl>
92Description:
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
Rafael J. Wysockicb8f51b2011-02-08 23:26:02 +010097 system from sleep states, this attribute is not present.
Rafael J. Wysocki074037e2010-09-22 22:09:10 +020098
Rafael J. Wysocki30e3ce62012-04-29 22:52:52 +020099What: /sys/devices/.../power/wakeup_abort_count
100Date: February 2012
Rafael J. Wysocki074037e2010-09-22 22:09:10 +0200101Contact: Rafael J. Wysocki <rjw@sisk.pl>
102Description:
Rafael J. Wysocki30e3ce62012-04-29 22:52:52 +0200103 The /sys/devices/.../wakeup_abort_count attribute contains the
Rafael J. Wysocki074037e2010-09-22 22:09:10 +0200104 number of times the processing of a wakeup event associated with
Rafael J. Wysocki30e3ce62012-04-29 22:52:52 +0200105 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
110What: /sys/devices/.../power/wakeup_expire_count
111Date: February 2012
112Contact: Rafael J. Wysocki <rjw@sisk.pl>
113Description:
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.
Rafael J. Wysocki074037e2010-09-22 22:09:10 +0200119
120What: /sys/devices/.../power/wakeup_active
121Date: September 2010
122Contact: Rafael J. Wysocki <rjw@sisk.pl>
123Description:
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
Rafael J. Wysockicb8f51b2011-02-08 23:26:02 +0100128 states, this attribute is not present.
Rafael J. Wysocki074037e2010-09-22 22:09:10 +0200129
130What: /sys/devices/.../power/wakeup_total_time_ms
131Date: September 2010
132Contact: Rafael J. Wysocki <rjw@sisk.pl>
133Description:
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,
Rafael J. Wysockicb8f51b2011-02-08 23:26:02 +0100138 this attribute is not present.
Rafael J. Wysocki074037e2010-09-22 22:09:10 +0200139
140What: /sys/devices/.../power/wakeup_max_time_ms
141Date: September 2010
142Contact: Rafael J. Wysocki <rjw@sisk.pl>
143Description:
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
Rafael J. Wysockicb8f51b2011-02-08 23:26:02 +0100148 states, this attribute is not present.
Rafael J. Wysocki074037e2010-09-22 22:09:10 +0200149
150What: /sys/devices/.../power/wakeup_last_time_ms
151Date: September 2010
152Contact: Rafael J. Wysocki <rjw@sisk.pl>
153Description:
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
Rafael J. Wysockicb8f51b2011-02-08 23:26:02 +0100159 attribute is not present.
Alan Stern15bcb91d2010-09-25 23:35:21 +0200160
Rafael J. Wysocki55850942012-04-29 22:53:32 +0200161What: /sys/devices/.../power/wakeup_prevent_sleep_time_ms
162Date: February 2012
163Contact: Rafael J. Wysocki <rjw@sisk.pl>
164Description:
165 The /sys/devices/.../wakeup_prevent_sleep_time_ms attribute
166 contains the total time the device has been preventing
Masanari Iida4e79162a2012-11-08 21:57:35 +0900167 opportunistic transitions to sleep states from occurring.
Rafael J. Wysocki55850942012-04-29 22:53:32 +0200168 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
Alan Stern15bcb91d2010-09-25 23:35:21 +0200172What: /sys/devices/.../power/autosuspend_delay_ms
173Date: September 2010
174Contact: Alan Stern <stern@rowland.harvard.edu>
175Description:
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.
Rafael J. Wysocki85dc0b82012-03-13 01:01:39 +0100189
190What: /sys/devices/.../power/pm_qos_latency_us
191Date: March 2012
192Contact: Rafael J. Wysocki <rjw@sisk.pl>
193Description:
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.
Rafael J. Wysockie39473d2012-10-24 02:08:18 +0200207
208What: /sys/devices/.../power/pm_qos_no_power_off
209Date: September 2012
210Contact: Rafael J. Wysocki <rjw@sisk.pl>
211Description:
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
223What: /sys/devices/.../power/pm_qos_remote_wakeup
224Date: September 2012
225Contact: Rafael J. Wysocki <rjw@sisk.pl>
226Description:
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.