Commit | Line | Data |
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971cb7fb RW |
1 | What: /sys/devices/.../power/ |
2 | Date: January 2009 | |
49db1903 | 3 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
971cb7fb RW |
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 | |
49db1903 | 11 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
971cb7fb RW |
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 | |
cb8f51bd RW |
32 | events this file is not present. In that case the device cannot |
33 | be enabled to wake up the system from sleep states. | |
971cb7fb RW |
34 | |
35 | What: /sys/devices/.../power/control | |
36 | Date: January 2009 | |
49db1903 | 37 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
971cb7fb RW |
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. | |
5a2eb858 RW |
53 | |
54 | What: /sys/devices/.../power/async | |
55 | Date: January 2009 | |
49db1903 | 56 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
5a2eb858 RW |
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. | |
074037ec RW |
79 | |
80 | What: /sys/devices/.../power/wakeup_count | |
81 | Date: September 2010 | |
49db1903 | 82 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
074037ec RW |
83 | Description: |
84 | The /sys/devices/.../wakeup_count attribute contains the number | |
85 | of signaled wakeup events associated with the device. This | |
d0549801 | 86 | attribute is read-only. If the device is not capable to wake up |
cb8f51bd | 87 | the system from sleep states, this attribute is not present. |
d0549801 GU |
88 | If the device is not enabled to wake up the system from sleep |
89 | states, this attribute is empty. | |
074037ec RW |
90 | |
91 | What: /sys/devices/.../power/wakeup_active_count | |
92 | Date: September 2010 | |
49db1903 | 93 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
074037ec RW |
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 | |
d0549801 GU |
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. | |
074037ec | 102 | |
30e3ce6d RW |
103 | What: /sys/devices/.../power/wakeup_abort_count |
104 | Date: February 2012 | |
49db1903 | 105 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
074037ec | 106 | Description: |
30e3ce6d | 107 | The /sys/devices/.../wakeup_abort_count attribute contains the |
074037ec | 108 | number of times the processing of a wakeup event associated with |
30e3ce6d RW |
109 | the device might have aborted system transition into a sleep |
110 | state in progress. This attribute is read-only. If the device | |
d0549801 GU |
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. | |
30e3ce6d RW |
114 | |
115 | What: /sys/devices/.../power/wakeup_expire_count | |
116 | Date: February 2012 | |
49db1903 | 117 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
30e3ce6d RW |
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 | |
d0549801 GU |
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. | |
074037ec RW |
126 | |
127 | What: /sys/devices/.../power/wakeup_active | |
128 | Date: September 2010 | |
49db1903 | 129 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
074037ec RW |
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. | |
d0549801 GU |
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. | |
074037ec RW |
138 | |
139 | What: /sys/devices/.../power/wakeup_total_time_ms | |
140 | Date: September 2010 | |
49db1903 | 141 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
074037ec RW |
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 | |
d0549801 GU |
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. | |
074037ec RW |
149 | |
150 | What: /sys/devices/.../power/wakeup_max_time_ms | |
151 | Date: September 2010 | |
49db1903 | 152 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
074037ec RW |
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. | |
d0549801 GU |
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. | |
074037ec RW |
161 | |
162 | What: /sys/devices/.../power/wakeup_last_time_ms | |
163 | Date: September 2010 | |
49db1903 | 164 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
074037ec RW |
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 | |
d0549801 GU |
171 | attribute is not present. If the device is not enabled to wake |
172 | up the system from sleep states, this attribute is empty. | |
15bcb91d | 173 | |
55850945 RW |
174 | What: /sys/devices/.../power/wakeup_prevent_sleep_time_ms |
175 | Date: February 2012 | |
49db1903 | 176 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
55850945 RW |
177 | Description: |
178 | The /sys/devices/.../wakeup_prevent_sleep_time_ms attribute | |
179 | contains the total time the device has been preventing | |
4e79162a | 180 | opportunistic transitions to sleep states from occurring. |
d0549801 | 181 | This attribute is read-only. If the device is not capable to |
55850945 | 182 | wake up the system from sleep states, this attribute is not |
d0549801 GU |
183 | present. If the device is not enabled to wake up the system |
184 | from sleep states, this attribute is empty. | |
55850945 | 185 | |
15bcb91d AS |
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. | |
85dc0b8a | 203 | |
2d984ad1 | 204 | What: /sys/devices/.../power/pm_qos_resume_latency_us |
85dc0b8a | 205 | Date: March 2012 |
49db1903 | 206 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
85dc0b8a RW |
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. | |
e39473d0 | 221 | |
2d984ad1 RW |
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 | ||
e39473d0 RW |
247 | What: /sys/devices/.../power/pm_qos_no_power_off |
248 | Date: September 2012 | |
49db1903 | 249 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
e39473d0 RW |
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 | |
49db1903 | 264 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
e39473d0 RW |
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. |