Rafael J. Wysocki | 84ed64e | 2006-08-30 23:38:06 +0200 | [diff] [blame] | 1 | What: /sys/power/ |
| 2 | Date: August 2006 |
Rafael J. Wysocki | 49db190 | 2013-10-09 01:47:53 +0200 | [diff] [blame] | 3 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
Rafael J. Wysocki | 84ed64e | 2006-08-30 23:38:06 +0200 | [diff] [blame] | 4 | Description: |
| 5 | The /sys/power directory will contain files that will |
| 6 | provide a unified interface to the power management |
| 7 | subsystem. |
| 8 | |
| 9 | What: /sys/power/state |
Rafael J. Wysocki | 0399d4d | 2014-05-26 13:40:59 +0200 | [diff] [blame] | 10 | Date: May 2014 |
Rafael J. Wysocki | 49db190 | 2013-10-09 01:47:53 +0200 | [diff] [blame] | 11 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
Rafael J. Wysocki | 84ed64e | 2006-08-30 23:38:06 +0200 | [diff] [blame] | 12 | Description: |
Rafael J. Wysocki | 0399d4d | 2014-05-26 13:40:59 +0200 | [diff] [blame] | 13 | The /sys/power/state file controls system sleep states. |
| 14 | Reading from this file returns the available sleep state |
| 15 | labels, which may be "mem", "standby", "freeze" and "disk" |
| 16 | (hibernation). The meanings of the first three labels depend on |
| 17 | the relative_sleep_states command line argument as follows: |
| 18 | 1) relative_sleep_states = 1 |
| 19 | "mem", "standby", "freeze" represent non-hibernation sleep |
| 20 | states from the deepest ("mem", always present) to the |
| 21 | shallowest ("freeze"). "standby" and "freeze" may or may |
| 22 | not be present depending on the capabilities of the |
| 23 | platform. "freeze" can only be present if "standby" is |
| 24 | present. |
| 25 | 2) relative_sleep_states = 0 (default) |
| 26 | "mem" - "suspend-to-RAM", present if supported. |
| 27 | "standby" - "power-on suspend", present if supported. |
| 28 | "freeze" - "suspend-to-idle", always present. |
Rafael J. Wysocki | 84ed64e | 2006-08-30 23:38:06 +0200 | [diff] [blame] | 29 | |
| 30 | Writing to this file one of these strings causes the system to |
Rafael J. Wysocki | 0399d4d | 2014-05-26 13:40:59 +0200 | [diff] [blame] | 31 | transition into the corresponding state, if available. See |
| 32 | Documentation/power/states.txt for a description of what |
| 33 | "suspend-to-RAM", "power-on suspend" and "suspend-to-idle" mean. |
Rafael J. Wysocki | 84ed64e | 2006-08-30 23:38:06 +0200 | [diff] [blame] | 34 | |
| 35 | What: /sys/power/disk |
Rafael J. Wysocki | b918f6e | 2006-11-02 22:07:19 -0800 | [diff] [blame] | 36 | Date: September 2006 |
Rafael J. Wysocki | 49db190 | 2013-10-09 01:47:53 +0200 | [diff] [blame] | 37 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
Rafael J. Wysocki | 84ed64e | 2006-08-30 23:38:06 +0200 | [diff] [blame] | 38 | Description: |
| 39 | The /sys/power/disk file controls the operating mode of the |
| 40 | suspend-to-disk mechanism. Reading from this file returns |
| 41 | the name of the method by which the system will be put to |
| 42 | sleep on the next suspend. There are four methods supported: |
| 43 | 'firmware' - means that the memory image will be saved to disk |
| 44 | by some firmware, in which case we also assume that the |
| 45 | firmware will handle the system suspend. |
| 46 | 'platform' - the memory image will be saved by the kernel and |
| 47 | the system will be put to sleep by the platform driver (e.g. |
| 48 | ACPI or other PM registers). |
| 49 | 'shutdown' - the memory image will be saved by the kernel and |
| 50 | the system will be powered off. |
| 51 | 'reboot' - the memory image will be saved by the kernel and |
| 52 | the system will be rebooted. |
| 53 | |
Rafael J. Wysocki | b918f6e | 2006-11-02 22:07:19 -0800 | [diff] [blame] | 54 | Additionally, /sys/power/disk can be used to turn on one of the |
| 55 | two testing modes of the suspend-to-disk mechanism: 'testproc' |
| 56 | or 'test'. If the suspend-to-disk mechanism is in the |
| 57 | 'testproc' mode, writing 'disk' to /sys/power/state will cause |
| 58 | the kernel to disable nonboot CPUs and freeze tasks, wait for 5 |
| 59 | seconds, unfreeze tasks and enable nonboot CPUs. If it is in |
| 60 | the 'test' mode, writing 'disk' to /sys/power/state will cause |
| 61 | the kernel to disable nonboot CPUs and freeze tasks, shrink |
| 62 | memory, suspend devices, wait for 5 seconds, resume devices, |
| 63 | unfreeze tasks and enable nonboot CPUs. Then, we are able to |
| 64 | look in the log messages and work out, for example, which code |
| 65 | is being slow and which device drivers are misbehaving. |
| 66 | |
Rafael J. Wysocki | 84ed64e | 2006-08-30 23:38:06 +0200 | [diff] [blame] | 67 | The suspend-to-disk method may be chosen by writing to this |
| 68 | file one of the accepted strings: |
| 69 | |
| 70 | 'firmware' |
| 71 | 'platform' |
| 72 | 'shutdown' |
| 73 | 'reboot' |
Rafael J. Wysocki | b918f6e | 2006-11-02 22:07:19 -0800 | [diff] [blame] | 74 | 'testproc' |
| 75 | 'test' |
Rafael J. Wysocki | 84ed64e | 2006-08-30 23:38:06 +0200 | [diff] [blame] | 76 | |
| 77 | It will only change to 'firmware' or 'platform' if the system |
| 78 | supports that. |
| 79 | |
| 80 | What: /sys/power/image_size |
| 81 | Date: August 2006 |
Rafael J. Wysocki | 49db190 | 2013-10-09 01:47:53 +0200 | [diff] [blame] | 82 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
Rafael J. Wysocki | 84ed64e | 2006-08-30 23:38:06 +0200 | [diff] [blame] | 83 | Description: |
| 84 | The /sys/power/image_size file controls the size of the image |
| 85 | created by the suspend-to-disk mechanism. It can be written a |
| 86 | string representing a non-negative integer that will be used |
| 87 | as an upper limit of the image size, in bytes. The kernel's |
| 88 | suspend-to-disk code will do its best to ensure the image size |
| 89 | will not exceed this number. However, if it turns out to be |
| 90 | impossible, the kernel will try to suspend anyway using the |
| 91 | smallest image possible. In particular, if "0" is written to |
| 92 | this file, the suspend image will be as small as possible. |
| 93 | |
| 94 | Reading from this file will display the current image size |
| 95 | limit, which is set to 500 MB by default. |
| 96 | |
| 97 | What: /sys/power/pm_trace |
| 98 | Date: August 2006 |
Rafael J. Wysocki | 49db190 | 2013-10-09 01:47:53 +0200 | [diff] [blame] | 99 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
Rafael J. Wysocki | 84ed64e | 2006-08-30 23:38:06 +0200 | [diff] [blame] | 100 | Description: |
| 101 | The /sys/power/pm_trace file controls the code which saves the |
| 102 | last PM event point in the RTC across reboots, so that you can |
| 103 | debug a machine that just hangs during suspend (or more |
| 104 | commonly, during resume). Namely, the RTC is only used to save |
| 105 | the last PM event point if this file contains '1'. Initially |
| 106 | it contains '0' which may be changed to '1' by writing a |
| 107 | string representing a nonzero integer into it. |
| 108 | |
| 109 | To use this debugging feature you should attempt to suspend |
| 110 | the machine, then reboot it and run |
| 111 | |
| 112 | dmesg -s 1000000 | grep 'hash matches' |
| 113 | |
James Hogan | d33ac60 | 2010-10-12 00:00:25 +0200 | [diff] [blame] | 114 | If you do not get any matches (or they appear to be false |
| 115 | positives), it is possible that the last PM event point |
| 116 | referred to a device created by a loadable kernel module. In |
| 117 | this case cat /sys/power/pm_trace_dev_match (see below) after |
| 118 | your system is started up and the kernel modules are loaded. |
| 119 | |
Rafael J. Wysocki | 84ed64e | 2006-08-30 23:38:06 +0200 | [diff] [blame] | 120 | CAUTION: Using it will cause your machine's real-time (CMOS) |
| 121 | clock to be set to a random invalid time after a resume. |
Rafael J. Wysocki | 0e06b4a | 2010-01-23 22:25:15 +0100 | [diff] [blame] | 122 | |
James Hogan | d33ac60 | 2010-10-12 00:00:25 +0200 | [diff] [blame] | 123 | What; /sys/power/pm_trace_dev_match |
| 124 | Date: October 2010 |
| 125 | Contact: James Hogan <james@albanarts.com> |
| 126 | Description: |
| 127 | The /sys/power/pm_trace_dev_match file contains the name of the |
| 128 | device associated with the last PM event point saved in the RTC |
| 129 | across reboots when pm_trace has been used. More precisely it |
| 130 | contains the list of current devices (including those |
| 131 | registered by loadable kernel modules since boot) which match |
| 132 | the device hash in the RTC at boot, with a newline after each |
| 133 | one. |
| 134 | |
| 135 | The advantage of this file over the hash matches printed to the |
| 136 | kernel log (see /sys/power/pm_trace), is that it includes |
| 137 | devices created after boot by loadable kernel modules. |
| 138 | |
| 139 | Due to the small hash size necessary to fit in the RTC, it is |
| 140 | possible that more than one device matches the hash, in which |
| 141 | case further investigation is required to determine which |
| 142 | device is causing the problem. Note that genuine RTC clock |
| 143 | values (such as when pm_trace has not been used), can still |
| 144 | match a device and output it's name here. |
| 145 | |
Rafael J. Wysocki | 0e06b4a | 2010-01-23 22:25:15 +0100 | [diff] [blame] | 146 | What: /sys/power/pm_async |
| 147 | Date: January 2009 |
Rafael J. Wysocki | 49db190 | 2013-10-09 01:47:53 +0200 | [diff] [blame] | 148 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
Rafael J. Wysocki | 0e06b4a | 2010-01-23 22:25:15 +0100 | [diff] [blame] | 149 | Description: |
| 150 | The /sys/power/pm_async file controls the switch allowing the |
| 151 | user space to enable or disable asynchronous suspend and resume |
| 152 | of devices. If enabled, this feature will cause some device |
| 153 | drivers' suspend and resume callbacks to be executed in parallel |
| 154 | with each other and with the main suspend thread. It is enabled |
| 155 | if this file contains "1", which is the default. It may be |
| 156 | disabled by writing "0" to this file, in which case all devices |
| 157 | will be suspended and resumed synchronously. |
Rafael J. Wysocki | c125e96 | 2010-07-05 22:43:53 +0200 | [diff] [blame] | 158 | |
| 159 | What: /sys/power/wakeup_count |
| 160 | Date: July 2010 |
Rafael J. Wysocki | 49db190 | 2013-10-09 01:47:53 +0200 | [diff] [blame] | 161 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
Rafael J. Wysocki | c125e96 | 2010-07-05 22:43:53 +0200 | [diff] [blame] | 162 | Description: |
| 163 | The /sys/power/wakeup_count file allows user space to put the |
| 164 | system into a sleep state while taking into account the |
| 165 | concurrent arrival of wakeup events. Reading from it returns |
| 166 | the current number of registered wakeup events and it blocks if |
| 167 | some wakeup events are being processed at the time the file is |
| 168 | read from. Writing to it will only succeed if the current |
| 169 | number of wakeup events is equal to the written value and, if |
| 170 | successful, will make the kernel abort a subsequent transition |
| 171 | to a sleep state if any wakeup events are reported after the |
| 172 | write has returned. |
Rafael J. Wysocki | ddeb648 | 2011-05-15 11:38:48 +0200 | [diff] [blame] | 173 | |
| 174 | What: /sys/power/reserved_size |
| 175 | Date: May 2011 |
Rafael J. Wysocki | 49db190 | 2013-10-09 01:47:53 +0200 | [diff] [blame] | 176 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
Rafael J. Wysocki | ddeb648 | 2011-05-15 11:38:48 +0200 | [diff] [blame] | 177 | Description: |
| 178 | The /sys/power/reserved_size file allows user space to control |
| 179 | the amount of memory reserved for allocations made by device |
| 180 | drivers during the "device freeze" stage of hibernation. It can |
| 181 | be written a string representing a non-negative integer that |
| 182 | will be used as the amount of memory to reserve for allocations |
| 183 | made by device drivers' "freeze" callbacks, in bytes. |
| 184 | |
| 185 | Reading from this file will display the current value, which is |
| 186 | set to 1 MB by default. |
Rafael J. Wysocki | 7483b4a | 2012-04-29 22:53:22 +0200 | [diff] [blame] | 187 | |
| 188 | What: /sys/power/autosleep |
| 189 | Date: April 2012 |
Rafael J. Wysocki | 49db190 | 2013-10-09 01:47:53 +0200 | [diff] [blame] | 190 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
Rafael J. Wysocki | 7483b4a | 2012-04-29 22:53:22 +0200 | [diff] [blame] | 191 | Description: |
| 192 | The /sys/power/autosleep file can be written one of the strings |
| 193 | returned by reads from /sys/power/state. If that happens, a |
| 194 | work item attempting to trigger a transition of the system to |
| 195 | the sleep state represented by that string is queued up. This |
| 196 | attempt will only succeed if there are no active wakeup sources |
| 197 | in the system at that time. After every execution, regardless |
| 198 | of whether or not the attempt to put the system to sleep has |
| 199 | succeeded, the work item requeues itself until user space |
| 200 | writes "off" to /sys/power/autosleep. |
| 201 | |
| 202 | Reading from this file causes the last string successfully |
| 203 | written to it to be returned. |
Rafael J. Wysocki | b86ff982 | 2012-04-29 22:53:42 +0200 | [diff] [blame] | 204 | |
| 205 | What: /sys/power/wake_lock |
| 206 | Date: February 2012 |
Rafael J. Wysocki | 49db190 | 2013-10-09 01:47:53 +0200 | [diff] [blame] | 207 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
Rafael J. Wysocki | b86ff982 | 2012-04-29 22:53:42 +0200 | [diff] [blame] | 208 | Description: |
| 209 | The /sys/power/wake_lock file allows user space to create |
| 210 | wakeup source objects and activate them on demand (if one of |
| 211 | those wakeup sources is active, reads from the |
| 212 | /sys/power/wakeup_count file block or return false). When a |
| 213 | string without white space is written to /sys/power/wake_lock, |
| 214 | it will be assumed to represent a wakeup source name. If there |
| 215 | is a wakeup source object with that name, it will be activated |
| 216 | (unless active already). Otherwise, a new wakeup source object |
| 217 | will be registered, assigned the given name and activated. |
| 218 | If a string written to /sys/power/wake_lock contains white |
| 219 | space, the part of the string preceding the white space will be |
| 220 | regarded as a wakeup source name and handled as descrived above. |
| 221 | The other part of the string will be regarded as a timeout (in |
| 222 | nanoseconds) such that the wakeup source will be automatically |
| 223 | deactivated after it has expired. The timeout, if present, is |
| 224 | set regardless of the current state of the wakeup source object |
| 225 | in question. |
| 226 | |
| 227 | Reads from this file return a string consisting of the names of |
| 228 | wakeup sources created with the help of it that are active at |
| 229 | the moment, separated with spaces. |
| 230 | |
| 231 | |
| 232 | What: /sys/power/wake_unlock |
| 233 | Date: February 2012 |
Rafael J. Wysocki | 49db190 | 2013-10-09 01:47:53 +0200 | [diff] [blame] | 234 | Contact: Rafael J. Wysocki <rjw@rjwysocki.net> |
Rafael J. Wysocki | b86ff982 | 2012-04-29 22:53:42 +0200 | [diff] [blame] | 235 | Description: |
| 236 | The /sys/power/wake_unlock file allows user space to deactivate |
| 237 | wakeup sources created with the help of /sys/power/wake_lock. |
| 238 | When a string is written to /sys/power/wake_unlock, it will be |
| 239 | assumed to represent the name of a wakeup source to deactivate. |
| 240 | If a wakeup source object of that name exists and is active at |
| 241 | the moment, it will be deactivated. |
| 242 | |
| 243 | Reads from this file return a string consisting of the names of |
| 244 | wakeup sources created with the help of /sys/power/wake_lock |
| 245 | that are inactive at the moment, separated with spaces. |
Sameer Nanda | 4b7760b | 2012-06-19 22:23:33 +0200 | [diff] [blame] | 246 | |
| 247 | What: /sys/power/pm_print_times |
| 248 | Date: May 2012 |
| 249 | Contact: Sameer Nanda <snanda@chromium.org> |
| 250 | Description: |
| 251 | The /sys/power/pm_print_times file allows user space to |
| 252 | control whether the time taken by devices to suspend and |
| 253 | resume is printed. These prints are useful for hunting down |
| 254 | devices that take too long to suspend or resume. |
| 255 | |
| 256 | Writing a "1" enables this printing while writing a "0" |
| 257 | disables it. The default value is "0". Reading from this file |
| 258 | will display the current value. |
Alexandra Yates | a6f5f0d | 2015-09-15 10:32:46 -0700 | [diff] [blame] | 259 | |
| 260 | What: /sys/power/pm_wakeup_irq |
| 261 | Date: April 2015 |
| 262 | Contact: Alexandra Yates <alexandra.yates@linux.intel.org> |
| 263 | Description: |
| 264 | The /sys/power/pm_wakeup_irq file reports to user space the IRQ |
| 265 | number of the first wakeup interrupt (that is, the first |
| 266 | interrupt from an IRQ line armed for system wakeup) seen by the |
| 267 | kernel during the most recent system suspend/resume cycle. |
| 268 | |
| 269 | This output is useful for system wakeup diagnostics of spurious |
| 270 | wakeup interrupts. |