1 What: /sys/devices/.../power/ 1 What: /sys/devices/.../power/
2 Date: January 2009 2 Date: January 2009
3 Contact: Rafael J. Wysocki <rjw@rjwysock 3 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
4 Description: 4 Description:
5 The /sys/devices/.../power dir 5 The /sys/devices/.../power directory contains attributes
6 allowing the user space to che 6 allowing the user space to check and modify some power
7 management related properties 7 management related properties of given device.
8 8
9 What: /sys/devices/.../power/wakeup 9 What: /sys/devices/.../power/wakeup
10 Date: January 2009 10 Date: January 2009
11 Contact: Rafael J. Wysocki <rjw@rjwysock 11 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
12 Description: 12 Description:
13 The /sys/devices/.../power/wak 13 The /sys/devices/.../power/wakeup attribute allows the user
14 space to check if the device i 14 space to check if the device is enabled to wake up the system
15 from sleep states, such as the 15 from sleep states, such as the memory sleep state (suspend to
16 RAM) and hibernation (suspend 16 RAM) and hibernation (suspend to disk), and to enable or disable
17 it to do that as desired. 17 it to do that as desired.
18 18
19 Some devices support "wakeup" 19 Some devices support "wakeup" events, which are hardware signals
20 used to activate the system fr 20 used to activate the system from a sleep state. Such devices
21 have one of the following two 21 have one of the following two values for the sysfs power/wakeup
22 file: 22 file:
23 23
24 + "enabled\n" to issue the eve 24 + "enabled\n" to issue the events;
25 + "disabled\n" not to do so; 25 + "disabled\n" not to do so;
26 26
27 In that cases the user space c 27 In that cases the user space can change the setting represented
28 by the contents of this file b 28 by the contents of this file by writing either "enabled", or
29 "disabled" to it. 29 "disabled" to it.
30 30
31 For the devices that are not c 31 For the devices that are not capable of generating system wakeup
32 events this file is not presen 32 events this file is not present. In that case the device cannot
33 be enabled to wake up the syst 33 be enabled to wake up the system from sleep states.
34 34
35 What: /sys/devices/.../power/control 35 What: /sys/devices/.../power/control
36 Date: January 2009 36 Date: January 2009
37 Contact: Rafael J. Wysocki <rjw@rjwysock 37 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
38 Description: 38 Description:
39 The /sys/devices/.../power/con 39 The /sys/devices/.../power/control attribute allows the user
40 space to control the run-time 40 space to control the run-time power management of the device.
41 41
42 All devices have one of the fo 42 All devices have one of the following two values for the
43 power/control file: 43 power/control file:
44 44
45 + "auto\n" to allow the device 45 + "auto\n" to allow the device to be power managed at run time;
46 + "on\n" to prevent the device 46 + "on\n" to prevent the device from being power managed;
47 47
48 The default for all devices is 48 The default for all devices is "auto", which means that they may
49 be subject to automatic power 49 be subject to automatic power management, depending on their
50 drivers. Changing this attrib 50 drivers. Changing this attribute to "on" prevents the driver
51 from power managing the device 51 from power managing the device at run time. Doing that while
52 the device is suspended causes 52 the device is suspended causes it to be woken up.
53 53
54 What: /sys/devices/.../power/async 54 What: /sys/devices/.../power/async
55 Date: January 2009 55 Date: January 2009
56 Contact: Rafael J. Wysocki <rjw@rjwysock 56 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
57 Description: 57 Description:
58 The /sys/devices/.../async att 58 The /sys/devices/.../async attribute allows the user space to
59 enable or diasble the device's 59 enable or diasble the device's suspend and resume callbacks to
60 be executed asynchronously (ie 60 be executed asynchronously (ie. in separate threads, in parallel
61 with the main suspend/resume t 61 with the main suspend/resume thread) during system-wide power
62 transitions (eg. suspend to RA 62 transitions (eg. suspend to RAM, hibernation).
63 63
64 All devices have one of the fo 64 All devices have one of the following two values for the
65 power/async file: 65 power/async file:
66 66
67 + "enabled\n" to permit the as 67 + "enabled\n" to permit the asynchronous suspend/resume;
68 + "disabled\n" to forbid it; 68 + "disabled\n" to forbid it;
69 69
70 The value of this attribute ma 70 The value of this attribute may be changed by writing either
71 "enabled", or "disabled" to it 71 "enabled", or "disabled" to it.
72 72
73 It generally is unsafe to perm 73 It generally is unsafe to permit the asynchronous suspend/resume
74 of a device unless it is certa 74 of a device unless it is certain that all of the PM dependencies
75 of the device are known to the 75 of the device are known to the PM core. However, for some
76 devices this attribute is set 76 devices this attribute is set to "enabled" by bus type code or
77 device drivers and in that cas 77 device drivers and in that cases it should be safe to leave the
78 default value. 78 default value.
79 79
80 What: /sys/devices/.../power/wakeup_ 80 What: /sys/devices/.../power/wakeup_count
81 Date: September 2010 81 Date: September 2010
82 Contact: Rafael J. Wysocki <rjw@rjwysock 82 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
83 Description: 83 Description:
84 The /sys/devices/.../wakeup_co 84 The /sys/devices/.../wakeup_count attribute contains the number
85 of signaled wakeup events asso 85 of signaled wakeup events associated with the device. This
86 attribute is read-only. If th 86 attribute is read-only. If the device is not capable to wake up
87 the system from sleep states, 87 the system from sleep states, this attribute is not present.
88 If the device is not enabled t 88 If the device is not enabled to wake up the system from sleep
89 states, this attribute is empt 89 states, this attribute is empty.
90 90
91 What: /sys/devices/.../power/wakeup_ 91 What: /sys/devices/.../power/wakeup_active_count
92 Date: September 2010 92 Date: September 2010
93 Contact: Rafael J. Wysocki <rjw@rjwysock 93 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
94 Description: 94 Description:
95 The /sys/devices/.../wakeup_ac 95 The /sys/devices/.../wakeup_active_count attribute contains the
96 number of times the processing 96 number of times the processing of wakeup events associated with
97 the device was completed (at t 97 the device was completed (at the kernel level). This attribute
98 is read-only. If the device i 98 is read-only. If the device is not capable to wake up the
99 system from sleep states, this 99 system from sleep states, this attribute is not present. If
100 the device is not enabled to w 100 the device is not enabled to wake up the system from sleep
101 states, this attribute is empt 101 states, this attribute is empty.
102 102
103 What: /sys/devices/.../power/wakeup_ 103 What: /sys/devices/.../power/wakeup_abort_count
104 Date: February 2012 104 Date: February 2012
105 Contact: Rafael J. Wysocki <rjw@rjwysock 105 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
106 Description: 106 Description:
107 The /sys/devices/.../wakeup_ab 107 The /sys/devices/.../wakeup_abort_count attribute contains the
108 number of times the processing 108 number of times the processing of a wakeup event associated with
109 the device might have aborted 109 the device might have aborted system transition into a sleep
110 state in progress. This attri 110 state in progress. This attribute is read-only. If the device
111 is not capable to wake up the 111 is not capable to wake up the system from sleep states, this
112 attribute is not present. If 112 attribute is not present. If the device is not enabled to wake
113 up the system from sleep state 113 up the system from sleep states, this attribute is empty.
114 114
115 What: /sys/devices/.../power/wakeup_ 115 What: /sys/devices/.../power/wakeup_expire_count
116 Date: February 2012 116 Date: February 2012
117 Contact: Rafael J. Wysocki <rjw@rjwysock 117 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
118 Description: 118 Description:
119 The /sys/devices/.../wakeup_ex 119 The /sys/devices/.../wakeup_expire_count attribute contains the
120 number of times a wakeup event 120 number of times a wakeup event associated with the device has
121 been reported with a timeout t 121 been reported with a timeout that expired. This attribute is
122 read-only. If the device is n 122 read-only. If the device is not capable to wake up the system
123 from sleep states, this attrib 123 from sleep states, this attribute is not present. If the
124 device is not enabled to wake 124 device is not enabled to wake up the system from sleep states,
125 this attribute is empty. 125 this attribute is empty.
126 126
127 What: /sys/devices/.../power/wakeup_ 127 What: /sys/devices/.../power/wakeup_active
128 Date: September 2010 128 Date: September 2010
129 Contact: Rafael J. Wysocki <rjw@rjwysock 129 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
130 Description: 130 Description:
131 The /sys/devices/.../wakeup_ac 131 The /sys/devices/.../wakeup_active attribute contains either 1,
132 or 0, depending on whether or 132 or 0, depending on whether or not a wakeup event associated with
133 the device is being processed 133 the device is being processed (1). This attribute is read-only.
134 If the device is not capable t 134 If the device is not capable to wake up the system from sleep
135 states, this attribute is not 135 states, this attribute is not present. If the device is not
136 enabled to wake up the system 136 enabled to wake up the system from sleep states, this attribute
137 is empty. 137 is empty.
138 138
139 What: /sys/devices/.../power/wakeup_ 139 What: /sys/devices/.../power/wakeup_total_time_ms
140 Date: September 2010 140 Date: September 2010
141 Contact: Rafael J. Wysocki <rjw@rjwysock 141 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
142 Description: 142 Description:
143 The /sys/devices/.../wakeup_to 143 The /sys/devices/.../wakeup_total_time_ms attribute contains
144 the total time of processing w 144 the total time of processing wakeup events associated with the
145 device, in milliseconds. This 145 device, in milliseconds. This attribute is read-only. If the
146 device is not capable to wake 146 device is not capable to wake up the system from sleep states,
147 this attribute is not present. 147 this attribute is not present. If the device is not enabled to
148 wake up the system from sleep 148 wake up the system from sleep states, this attribute is empty.
149 149
150 What: /sys/devices/.../power/wakeup_ 150 What: /sys/devices/.../power/wakeup_max_time_ms
151 Date: September 2010 151 Date: September 2010
152 Contact: Rafael J. Wysocki <rjw@rjwysock 152 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
153 Description: 153 Description:
154 The /sys/devices/.../wakeup_ma 154 The /sys/devices/.../wakeup_max_time_ms attribute contains
155 the maximum time of processing 155 the maximum time of processing a single wakeup event associated
156 with the device, in millisecon 156 with the device, in milliseconds. This attribute is read-only.
157 If the device is not capable t 157 If the device is not capable to wake up the system from sleep
158 states, this attribute is not 158 states, this attribute is not present. If the device is not
159 enabled to wake up the system 159 enabled to wake up the system from sleep states, this attribute
160 is empty. 160 is empty.
161 161
162 What: /sys/devices/.../power/wakeup_ 162 What: /sys/devices/.../power/wakeup_last_time_ms
163 Date: September 2010 163 Date: September 2010
164 Contact: Rafael J. Wysocki <rjw@rjwysock 164 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
165 Description: 165 Description:
166 The /sys/devices/.../wakeup_la 166 The /sys/devices/.../wakeup_last_time_ms attribute contains
167 the value of the monotonic clo 167 the value of the monotonic clock corresponding to the time of
168 signaling the last wakeup even 168 signaling the last wakeup event associated with the device, in
169 milliseconds. This attribute 169 milliseconds. This attribute is read-only. If the device is
170 not enabled to wake up the sys 170 not enabled to wake up the system from sleep states, this
171 attribute is not present. If 171 attribute is not present. If the device is not enabled to wake
172 up the system from sleep state 172 up the system from sleep states, this attribute is empty.
173 173
174 What: /sys/devices/.../power/wakeup_ 174 What: /sys/devices/.../power/wakeup_prevent_sleep_time_ms
175 Date: February 2012 175 Date: February 2012
176 Contact: Rafael J. Wysocki <rjw@rjwysock 176 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
177 Description: 177 Description:
178 The /sys/devices/.../wakeup_pr 178 The /sys/devices/.../wakeup_prevent_sleep_time_ms attribute
179 contains the total time the de 179 contains the total time the device has been preventing
180 opportunistic transitions to s 180 opportunistic transitions to sleep states from occurring.
181 This attribute is read-only. 181 This attribute is read-only. If the device is not capable to
182 wake up the system from sleep 182 wake up the system from sleep states, this attribute is not
183 present. If the device is not 183 present. If the device is not enabled to wake up the system
184 from sleep states, this attrib 184 from sleep states, this attribute is empty.
185 185
186 What: /sys/devices/.../power/autosus 186 What: /sys/devices/.../power/autosuspend_delay_ms
187 Date: September 2010 187 Date: September 2010
188 Contact: Alan Stern <stern@rowland.harva 188 Contact: Alan Stern <stern@rowland.harvard.edu>
189 Description: 189 Description:
190 The /sys/devices/.../power/aut 190 The /sys/devices/.../power/autosuspend_delay_ms attribute
191 contains the autosuspend delay 191 contains the autosuspend delay value (in milliseconds). Some
192 drivers do not want their devi 192 drivers do not want their device to suspend as soon as it
193 becomes idle at run time; they 193 becomes idle at run time; they want the device to remain
194 inactive for a certain minimum 194 inactive for a certain minimum period of time first. That
195 period is called the autosuspe 195 period is called the autosuspend delay. Negative values will
196 prevent the device from being 196 prevent the device from being suspended at run time (similar
197 to writing "on" to the power/c 197 to writing "on" to the power/control attribute). Values >=
198 1000 will cause the autosuspen 198 1000 will cause the autosuspend timer expiration to be rounded
199 up to the nearest second. 199 up to the nearest second.
200 200
201 Not all drivers support this a 201 Not all drivers support this attribute. If it isn't supported,
202 attempts to read or write it w 202 attempts to read or write it will yield I/O errors.
203 203
204 What: /sys/devices/.../power/pm_qos_ 204 What: /sys/devices/.../power/pm_qos_resume_latency_us
205 Date: March 2012 205 Date: March 2012
206 Contact: Rafael J. Wysocki <rjw@rjwysock 206 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
207 Description: 207 Description:
208 The /sys/devices/.../power/pm_ 208 The /sys/devices/.../power/pm_qos_resume_latency_us attribute
209 contains the PM QoS resume lat 209 contains the PM QoS resume latency limit for the given device,
210 which is the maximum allowed t 210 which is the maximum allowed time it can take to resume the
211 device, after it has been susp 211 device, after it has been suspended at run time, from a resume
212 request to the moment the devi 212 request to the moment the device will be ready to process I/O,
213 in microseconds. If it is equ 213 in microseconds. If it is equal to 0, however, this means that
214 the PM QoS resume latency may 214 the PM QoS resume latency may be arbitrary and the special value
215 "n/a" means that user space ca 215 "n/a" means that user space cannot accept any resume latency at
216 all for the given device. 216 all for the given device.
217 217
218 Not all drivers support this a 218 Not all drivers support this attribute. If it isn't supported,
219 it is not present. 219 it is not present.
220 220
221 This attribute has no effect o 221 This attribute has no effect on system-wide suspend/resume and
222 hibernation. 222 hibernation.
223 223
224 What: /sys/devices/.../power/pm_qos_ 224 What: /sys/devices/.../power/pm_qos_latency_tolerance_us
225 Date: January 2014 225 Date: January 2014
226 Contact: Rafael J. Wysocki <rjw@rjwysock 226 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
227 Description: 227 Description:
228 The /sys/devices/.../power/pm_ 228 The /sys/devices/.../power/pm_qos_latency_tolerance_us attribute
229 contains the PM QoS active sta 229 contains the PM QoS active state latency tolerance limit for the
230 given device in microseconds. 230 given device in microseconds. That is the maximum memory access
231 latency the device can suffer 231 latency the device can suffer without any visible adverse
232 effects on user space function 232 effects on user space functionality. If that value is the
233 string "any", the latency does 233 string "any", the latency does not matter to user space at all,
234 but hardware should not be all 234 but hardware should not be allowed to set the latency tolerance
235 for the device automatically. 235 for the device automatically.
236 236
237 Reading "auto" from this file 237 Reading "auto" from this file means that the maximum memory
238 access latency for the device 238 access latency for the device may be determined automatically
239 by the hardware as needed. Wr 239 by the hardware as needed. Writing "auto" to it allows the
240 hardware to be switched to thi 240 hardware to be switched to this mode if there are no other
241 latency tolerance requirements 241 latency tolerance requirements from the kernel side.
242 242
243 This attribute is only present 243 This attribute is only present if the feature controlled by it
244 is supported by the hardware. 244 is supported by the hardware.
245 245
246 This attribute has no effect o 246 This attribute has no effect on runtime suspend and resume of
247 devices and on system-wide sus 247 devices and on system-wide suspend/resume and hibernation.
248 248
249 What: /sys/devices/.../power/pm_qos_ 249 What: /sys/devices/.../power/pm_qos_no_power_off
250 Date: September 2012 250 Date: September 2012
251 Contact: Rafael J. Wysocki <rjw@rjwysock 251 Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
252 Description: 252 Description:
253 The /sys/devices/.../power/pm_ 253 The /sys/devices/.../power/pm_qos_no_power_off attribute
254 is used for manipulating the P 254 is used for manipulating the PM QoS "no power off" flag. If
255 set, this flag indicates to th 255 set, this flag indicates to the kernel that power should not
256 be removed entirely from the d 256 be removed entirely from the device.
257 257
258 Not all drivers support this a 258 Not all drivers support this attribute. If it isn't supported,
259 it is not present. 259 it is not present.
260 260
261 This attribute has no effect o 261 This attribute has no effect on system-wide suspend/resume and
262 hibernation. 262 hibernation.
263 <<
264 What: /sys/devices/.../power/runtime <<
265 Date: April 2010 <<
266 Contact: Rafael J. Wysocki <rjw@rjwysock <<
267 Description: <<
268 The /sys/devices/.../power/run <<
269 the current runtime PM status <<
270 "suspended", "suspending", "re <<
271 error), or "unsupported" (runt <<
272 <<
273 What: /sys/devices/.../power/runtime <<
274 Date: Jul 2010 <<
275 Contact: Arjan van de Ven <arjan@linux.i <<
276 Description: <<
277 Reports the total time that th <<
278 Used for runtime PM statistics <<
279 <<
280 What: /sys/devices/.../power/runtime <<
281 Date: Jul 2010 <<
282 Contact: Arjan van de Ven <arjan@linux.i <<
283 Description: <<
284 Reports total time that the de <<
285 Used for runtime PM statistics <<
286 <<
287 What: /sys/devices/.../power/runtime <<
288 Date: Apr 2010 <<
289 Contact: Dominik Brodowski <linux@domini <<
290 Description: <<
291 Reports the runtime PM usage c <<
292 <<
293 What: /sys/devices/.../power/runtime <<
294 Date: Apr 2010 <<
295 Contact: Dominik Brodowski <linux@domini <<
296 Description: <<
297 Is runtime PM enabled for this <<
298 States are "enabled", "disable <<
299 combination of the latter two. <<
300 <<
301 What: /sys/devices/.../power/runtime <<
302 Date: Apr 2010 <<
303 Contact: Dominik Brodowski <linux@domini <<
304 Description: <<
305 Reports the runtime PM childre <<
306 0 if the children will be igno <<
307 <<
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.