Lines Matching +full:suspend +full:- +full:in +full:- +full:wait
5 (C) 2009-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
17 * The power management workqueue pm_wq in which bus types and device drivers can
18 put their PM-related work items. It is strongly recommended that pm_wq be
20 them to be synchronized with system-wide power transitions (suspend to RAM,
21 hibernation and resume from system sleep states). pm_wq is declared in
22 include/linux/pm_runtime.h and defined in kernel/power/main.c.
24 * A number of runtime PM fields in the 'power' member of 'struct device' (which
25 is of the type 'struct dev_pm_info', defined in include/linux/pm.h) that can
28 * Three device runtime PM callbacks in 'struct dev_pm_ops' (defined in
31 * A set of helper functions defined in drivers/base/power/runtime.c that can be
32 used for carrying out runtime PM operations in such a way that the
36 The runtime PM callbacks present in 'struct dev_pm_ops', the device runtime PM
43 There are three device runtime PM callbacks defined in 'struct dev_pm_ops'::
53 The ->runtime_suspend(), ->runtime_resume() and ->runtime_idle() callbacks
57 1. PM domain of the device, if the device's PM domain object, dev->pm_domain,
60 2. Device type of the device, if both dev->type and dev->type->pm are present.
62 3. Device class of the device, if both dev->class and dev->class->pm are
65 4. Bus type of the device, if both dev->bus and dev->bus->pm are present.
68 callback, the PM core will invoke the corresponding driver callback stored in
69 dev->driver->pm directly (if present).
71 The PM core always checks which callback to use in the order given above, so the
73 and bus type. Moreover, the high-priority one will always take precedence over
74 a low-priority one. The PM domain, bus type, device type and class callbacks
75 are referred to as subsystem-level callbacks in what follows.
77 By default, the callbacks are always invoked in process context with interrupts
79 the PM core that it is safe to run the ->runtime_suspend(), ->runtime_resume()
80 and ->runtime_idle() callbacks for the given device in atomic context with
81 interrupts disabled. This implies that the callback routines in question must
84 handler or generally in an atomic context.
86 The subsystem-level suspend callback, if present, is _entirely_ _responsible_
87 for handling the suspend of the device as appropriate, which may, but need not
88 include executing the device driver's own ->runtime_suspend() callback (from the
89 PM core's point of view it is not necessary to implement a ->runtime_suspend()
90 callback in a device driver as long as the subsystem-level suspend callback
93 * Once the subsystem-level suspend callback (or the driver suspend callback,
99 PM status of a device after successful execution of the suspend callback is
102 * If the suspend callback returns -EBUSY or -EAGAIN, the device's runtime PM
106 * If the suspend callback returns an error code different from -EBUSY and
107 -EAGAIN, the PM core regards this as a fatal error and will refuse to run
108 the helper functions described in Section 4 for the device until its status
112 In particular, if the driver requires remote wakeup capability (i.e. hardware
115 device, then ->runtime_suspend() should return -EBUSY. On the other hand, if
117 low-power state during the execution of the suspend callback, it is expected
119 should be enabled for all input devices put into low-power states at run time.
121 The subsystem-level resume callback, if present, is **entirely responsible** for
123 include executing the device driver's own ->runtime_resume() callback (from the
124 PM core's point of view it is not necessary to implement a ->runtime_resume()
125 callback in a device driver as long as the subsystem-level resume callback knows
128 * Once the subsystem-level resume callback (or the driver resume callback, if
135 fatal error and will refuse to run the helper functions described in Section
140 The idle callback (a subsystem-level one, if present, or the driver one) is
151 (or driver) in question, but the expected and recommended action is to check
153 suspending the device are satisfied) and to queue up a suspend request for the
154 device in that case. If there is no idle callback, or if the callback returns
155 0, then the PM core will attempt to carry out a runtime suspend of the device,
156 also respecting devices configured for autosuspend. In essence this means a
160 started a delayed suspend), the routine must return a non-zero value. Negative
163 The helper functions provided by the PM core, described in Section 4, guarantee
168 ->runtime_suspend() in parallel with ->runtime_resume() or with another
169 instance of ->runtime_suspend() for the same device) with the exception that
170 ->runtime_suspend() or ->runtime_resume() can be executed in parallel with
171 ->runtime_idle() (although ->runtime_idle() will not be started while any
174 (2) ->runtime_idle() and ->runtime_suspend() can only be executed for 'active'
175 devices (i.e. the PM core will only execute ->runtime_idle() or
176 ->runtime_suspend() for the devices the runtime PM status of which is
179 (3) ->runtime_idle() and ->runtime_suspend() can only be executed for a device
184 (4) ->runtime_resume() can only be executed for 'suspended' devices (i.e. the
185 PM core will only execute ->runtime_resume() for the devices the runtime
191 * If ->runtime_suspend() is about to be executed or there's a pending request
192 to execute it, ->runtime_idle() will not be executed for the same device.
194 * A request to execute or to schedule the execution of ->runtime_suspend()
195 will cancel any pending requests to execute ->runtime_idle() for the same
198 * If ->runtime_resume() is about to be executed or there's a pending request
201 * A request to execute ->runtime_resume() will cancel any pending or
208 The following device runtime PM fields are present in 'struct dev_pm_info', as
209 defined in include/linux/pm.h:
212 - timer used for scheduling (delayed) suspend and autosuspend requests
215 - timer expiration time, in jiffies (if this is different from zero, the
220 - work structure used for queuing up requests (i.e. work items in pm_wq)
223 - wait queue used if any of the helper functions needs to wait for another
227 - lock used for synchronization
230 - the usage counter of the device
233 - the count of 'active' children of the device
236 - if set, the value of child_count is ignored (but still updated)
239 - used for disabling the helper functions (they work normally if this is
244 - if set, there was a fatal error (one of the callbacks returned error code
245 as described in Section 2), so the helper functions will not work until
250 - if set, ->runtime_idle() is being executed
253 - if set, there's a pending request (i.e. a work item queued up into pm_wq)
256 - type of request that's pending (valid if request_pending is set)
259 - set if ->runtime_resume() is about to be run while ->runtime_suspend() is
260 being executed for that device and it is not practical to wait for the
261 suspend to complete; means "start a resume as soon as you've suspended"
264 - the runtime PM status of the device; this field's initial value is
269 - the last runtime PM status of the device captured before disabling runtime
273 - if set, indicates that the user space has allowed the device driver to
279 - indicates that the device does not use the runtime PM callbacks (see
284 - indicates that the ->runtime_suspend() and ->runtime_resume() callbacks
288 - indicates that the device's driver supports delayed autosuspend (see
293 - indicates that the PM core should attempt to carry out an autosuspend
294 when the timer expires rather than a normal suspend
297 - the delay time (in milliseconds) to be used for autosuspend
300 - the time (in jiffies) when the pm_runtime_mark_last_busy() helper
301 function was last called for this device; used in calculating inactivity
309 The following runtime PM helper functions are defined in
313 - initialize the device runtime PM fields in 'struct dev_pm_info'
316 - make sure that the runtime PM of the device will be disabled after
320 - execute the subsystem-level idle callback for the device; returns an
321 error code on failure, where -EINPROGRESS means that ->runtime_idle() is
326 - execute the subsystem-level suspend callback for the device; returns 0 on
328 error code on failure, where -EAGAIN or -EBUSY means it is safe to attempt
329 to suspend the device again in future and -EACCES means that
333 - same as pm_runtime_suspend() except that the autosuspend delay is taken
339 - execute the subsystem-level resume callback for the device; returns 0 on
342 changing from 0 to 1) or error code on failure, where -EAGAIN means it may
343 be safe to attempt to resume the device again in future, but
344 'power.runtime_error' should be checked additionally, and -EACCES means
349 - run pm_runtime_resume(dev) and if successful, increment the device's
353 - submit a request to execute the subsystem-level idle callback for the
354 device (the request is represented by a work item in pm_wq); returns 0 on
358 - schedule the execution of the subsystem-level suspend callback for the
363 - schedule the execution of the subsystem-level suspend callback for the
364 device in future, where 'delay' is the time to wait before queuing up a
365 suspend work item in pm_wq, in milliseconds (if 'delay' is zero, the work
369 ->runtime_suspend() is already scheduled and not yet expired, the new
370 value of 'delay' will be used as the time to wait
373 - submit a request to execute the subsystem-level resume callback for the
374 device (the request is represented by a work item in pm_wq); returns 0 on
379 - increment the device's usage counter
382 - increment the device's usage counter, run pm_request_resume(dev) and
386 - increment the device's usage counter, run pm_runtime_resume(dev) and
391 result in cleaner code.
394 - return -EINVAL if 'power.disable_depth' is nonzero; otherwise, if the
400 - return -EINVAL if 'power.disable_depth' is nonzero; otherwise, if the
405 - decrement the device's usage counter
408 - decrement the device's usage counter; if the result is 0 then run
412 - does the same as __pm_runtime_put_autosuspend() for now, but in the
416 - decrement the device's usage counter; if the result is 0 then run
420 - decrement the device's usage counter; if the result is 0 then run
424 - decrement the device's usage counter; if the result is 0 then run
428 - decrement the device's usage counter; if the result is 0 then run
432 - decrement the device's 'power.disable_depth' field; if that field is equal
433 to zero, the runtime PM helper functions can execute subsystem-level
434 callbacks described in Section 2 for the device
437 - increment the device's 'power.disable_depth' field (if the value of that
438 field was previously zero, this prevents subsystem-level runtime PM
442 necessary to execute the subsystem-level resume callback for the device
446 - check if there's a resume request pending for the device and resume it
447 (synchronously) in that case, cancel any other pending runtime PM requests
448 regarding it and wait for all runtime PM operations on it in progress to
450 necessary to execute the subsystem-level resume callback for the device to
454 - set/unset the power.ignore_children flag of the device
457 - clear the device's 'power.runtime_error' flag, set the device's runtime
465 - clear the device's 'power.runtime_error' flag, set the device's runtime
472 - return true if the device's runtime PM status is 'active' or its
476 - return true if the device's runtime PM status is 'suspended' and its
480 - return true if the device's runtime PM status is 'suspended'
483 - set the power.runtime_auto flag for the device and decrease its usage
488 - unset the power.runtime_auto flag for the device and increase its usage
493 - set the power.no_callbacks flag for the device and remove the runtime
498 - set the power.irq_safe flag for the device, causing the runtime-PM
502 - return true if power.irq_safe flag was set for the device, causing
503 the runtime-PM callbacks to be invoked with interrupts off
506 - set the power.last_busy field to the current time
509 - set the power.use_autosuspend flag, enabling autosuspend delays; call
514 - clear the power.use_autosuspend flag, disabling autosuspend delays;
519 - set the power.autosuspend_delay value to 'delay' (expressed in
528 - calculate the time when the current autosuspend delay period will expire,
533 in jiffies
537 - pm_request_idle()
538 - pm_request_autosuspend()
539 - pm_schedule_suspend()
540 - pm_request_resume()
541 - pm_runtime_get_noresume()
542 - pm_runtime_get()
543 - pm_runtime_put_noidle()
544 - pm_runtime_put()
545 - pm_runtime_put_autosuspend()
546 - __pm_runtime_put_autosuspend()
547 - pm_runtime_enable()
548 - pm_suspend_ignore_children()
549 - pm_runtime_set_active()
550 - pm_runtime_set_suspended()
551 - pm_runtime_suspended()
552 - pm_runtime_mark_last_busy()
553 - pm_runtime_autosuspend_expiration()
556 functions may also be used in interrupt context:
558 - pm_runtime_idle()
559 - pm_runtime_suspend()
560 - pm_runtime_autosuspend()
561 - pm_runtime_resume()
562 - pm_runtime_get_sync()
563 - pm_runtime_put_sync()
564 - pm_runtime_put_sync_suspend()
565 - pm_runtime_put_sync_autosuspend()
571 majority of the runtime PM helper functions described in Section 4 will return
572 -EAGAIN until pm_runtime_enable() is called for the device.
574 In addition to that, the initial runtime PM status of all devices is
582 the parent's 'power.ignore_children' flag is set. Namely, in that case the
583 parent won't be able to suspend at run time, using the PM core's helper
594 ->probe() callback will likely need to wake it up using one of the PM core's
595 helper functions described in Section 4. In that case, pm_runtime_resume()
600 if it is registered with a subsystem that may call back in) then the
605 It may be desirable to suspend the device once ->probe() has finished.
607 request to execute the subsystem-level idle callback for the device at that
609 update the last busy mark before returning from ->probe().
612 notifier callback in __device_release_driver(), which is necessary because the
616 resumes the device if it's in the suspended state and prevents it from
620 calling pm_runtime_suspend() from their ->remove() routines, the driver core
622 notifications in __device_release_driver(). This requires bus types and
623 drivers to make their ->remove() callbacks avoid races with runtime PM directly,
624 but it also allows more flexibility in the handling of devices during the
627 Drivers in ->remove() callback should undo the runtime PM changes done
628 in ->probe(). Usually this means calling pm_runtime_disable(),
633 attribute to "on", which causes pm_runtime_forbid() to be called. In principle,
646 Runtime PM and system sleep (i.e., system suspend and hibernation, also known
647 as suspend-to-RAM and suspend-to-disk) interact with each other in a couple of
651 The device may have different wake-up settings for runtime PM and system sleep.
652 For example, remote wake-up may be enabled for runtime suspend but disallowed
654 the subsystem-level system suspend callback is responsible for changing the
655 device's wake-up setting (it may leave that to the device driver's system
656 suspend routine). It may be necessary to resume the device and suspend it again
657 in order to do so. The same is true if the driver uses different power levels
658 or other settings for runtime suspend and system sleep.
661 power, even if they had been suspended before the system suspend began. There
664 * The device might need to switch power levels, wake-up settings, etc.
666 * Remote wake-up events might have been lost by the firmware.
668 * The device's children may need the device to be at full power in order
677 likely it would need a runtime resume in the near future anyway.
679 If the device had been suspended before the system suspend began and it's
681 to be updated to reflect the actual post-system sleep status. The way to do
684 - pm_runtime_disable(dev);
685 - pm_runtime_set_active(dev);
686 - pm_runtime_enable(dev);
689 ->suspend() callback and decrements it after calling the ->resume() callback.
691 suspend attempts to be permanently lost. If the usage count goes to zero
692 following the return of the ->resume() callback, the ->runtime_idle() callback
696 or hardware operation. Instead, all hardware components are put into low-power
697 states directly by the kernel in a coordinated way. Then, the system sleep
698 state effectively follows from the states the hardware components end up in
703 place (in particular, if the system is not waking up from hibernation), it may
705 suspend began in the suspended state.
708 different levels of device hierarchy. Namely, if a system suspend .prepare()
710 that the device appears to be runtime-suspended and its state is fine, so it
711 may be left in runtime suspend provided that all of its descendants are also
712 left in runtime suspend. If that happens, the PM core will not execute any
713 system suspend and resume callbacks for all of those devices, except for the
715 as appropriate. This only applies to system suspend transitions that are not
716 related to hibernation (see Documentation/driver-api/pm/devices.rst for more
720 the runtime PM and system suspend/resume (and hibernation) callbacks by carrying
723 * During system suspend pm_runtime_get_noresume() is called for every device
724 right before executing the subsystem-level .prepare() callback for it and
726 subsystem-level .suspend() callback for it. In addition to that the PM core
728 device right before executing the subsystem-level .suspend_late() callback
732 every device right after executing the subsystem-level .resume_early()
733 callback and right after executing the subsystem-level .complete() callback
740 management callbacks provided by the PM core, defined in
744 - invoke the ->runtime_suspend() callback provided by the driver of this
748 - invoke the ->runtime_resume() callback provided by the driver of this
752 - if the device has not been suspended at run time, invoke the ->suspend()
757 - if pm_runtime_suspended(dev) returns "false", invoke the ->suspend_noirq()
762 - invoke the ->resume() callback provided by the driver of this device and,
766 - invoke the ->resume_noirq() callback provided by the driver of this device
769 - if the device has not been suspended at run time, invoke the ->freeze()
774 - if pm_runtime_suspended(dev) returns "false", invoke the ->freeze_noirq()
779 - if the device has not been suspended at run time, invoke the ->thaw()
784 - if pm_runtime_suspended(dev) returns "false", invoke the ->thaw_noirq()
789 - if the device has not been suspended at run time, invoke the ->poweroff()
794 - if pm_runtime_suspended(dev) returns "false", run the ->poweroff_noirq()
799 - invoke the ->restore() callback provided by the driver of this device and,
803 - invoke the ->restore_noirq() callback provided by the device's driver
806 provide its own callbacks for ->runtime_idle(), ->runtime_suspend(),
807 ->runtime_resume(), ->suspend(), ->suspend_noirq(), ->resume(),
808 ->resume_noirq(), ->freeze(), ->freeze_noirq(), ->thaw(), ->thaw_noirq(),
809 ->poweroff(), ->poweroff_noirq(), ->restore(), ->restore_noirq() in the
810 subsystem-level dev_pm_ops structure.
812 Device drivers that wish to use the same function as a system suspend, freeze,
813 poweroff and runtime suspend callback, and similarly for system resume, thaw,
815 DEFINE_RUNTIME_DEV_PM_OPS() defined in include/linux/pm_runtime.h (possibly setting its
818 8. "No-Callback" Devices
821 Some "devices" are only logical sub-devices of their parent and cannot be
822 power-managed on their own. (The prototype example is a USB interface. Entire
823 USB devices can go into low-power mode or send wake-up requests, but neither is
825 need of runtime PM callbacks; if the callbacks did exist, ->runtime_suspend()
826 and ->runtime_resume() would always return 0 without doing anything else and
827 ->runtime_idle() would always call pm_runtime_suspend().
833 prevent the non-debugging runtime PM sysfs attributes from being created.
836 ->runtime_idle(), ->runtime_suspend(), or ->runtime_resume() callbacks.
845 Note that, in some cases it may not be desirable for subsystems/drivers to call
850 in subsystems/drivers, the PM core allows runtime PM callbacks to be
854 9. Autosuspend, or automatically-delayed suspends
858 A device should be put in a low-power state only when there's some reason to
859 think it will remain in that state for a substantial time. A common heuristic
863 the heuristic ends up being non-optimal, it will still prevent devices from
864 "bouncing" too rapidly between low-power and full-power states.
879 In order to use autosuspend, subsystems or drivers must call
882 instead of the non-autosuspend counterparts::
889 Drivers may also continue to use the non-autosuspend helper functions; they
895 autosuspend delay time has expired. If the ->runtime_suspend() callback
896 returns -EAGAIN or -EBUSY, and if the next autosuspend delay expiration time is
897 in the future (as it normally would be if the callback invoked
899 autosuspend. The ->runtime_suspend() callback can't do this rescheduling
900 itself because no suspend requests of any kind are accepted while the device is
903 The implementation is well suited for asynchronous use in interrupt contexts.
905 synchronize ->runtime_suspend() callbacks with the arrival of I/O requests.
907 Here is a schematic pseudo-code example::
911 lock(&foo->private_lock);
913 if (foo->num_pending_requests++ == 0)
914 pm_runtime_get(&foo->dev);
915 if (!foo->is_suspended)
917 unlock(&foo->private_lock);
922 lock(&foo->private_lock);
923 if (--foo->num_pending_requests == 0) {
924 pm_runtime_mark_last_busy(&foo->dev);
925 __pm_runtime_put_autosuspend(&foo->dev);
929 unlock(&foo->private_lock);
938 lock(&foo->private_lock);
939 if (foo->num_pending_requests > 0) {
940 ret = -EBUSY;
942 /* ... suspend the device ... */
943 foo->is_suspended = 1;
945 unlock(&foo->private_lock);
953 lock(&foo->private_lock);
955 foo->is_suspended = 0;
956 pm_runtime_mark_last_busy(&foo->dev);
957 if (foo->num_pending_requests > 0)
959 unlock(&foo->private_lock);
966 requests (while holding the private lock) before allowing the suspend to
969 In addition, the power.autosuspend_delay field can be changed by user space at
971 pm_runtime_autosuspend_expiration() from within the ->runtime_suspend()
974 -EAGAIN.