Lines Matching +full:autosuspend +full:- +full:period
5 (C) 2009-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
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,
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.
69 dev->driver->pm directly (if present).
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.
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
86 The subsystem-level suspend callback, if present, is _entirely_ _responsible_
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,
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
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
140 The idle callback (a subsystem-level one, if present, or the driver one) is
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
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
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
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
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
297 - the delay time (in milliseconds) to be used for autosuspend
300 - the time (in jiffies) when the pm_runtime_mark_last_busy() helper
302 periods for autosuspend
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
335 not yet expired then an autosuspend is scheduled for the appropriate time
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
344 'power.runtime_error' should be checked additionally, and -EACCES means
349 - run pm_runtime_resume(dev) and if successful, increment the device's
355 - submit a request to execute the subsystem-level idle callback for the
360 - schedule the execution of the subsystem-level suspend callback for the
361 device when the autosuspend delay has expired; if the delay has already
365 - schedule the execution of the subsystem-level suspend callback for the
371 ->runtime_suspend() is already scheduled and not yet expired, the new
375 - submit a request to execute the subsystem-level resume callback for the
381 - increment the device's usage counter
384 - increment the device's usage counter, run pm_request_resume(dev) and
388 - increment the device's usage counter, run pm_runtime_resume(dev) and
396 - return -EINVAL if 'power.disable_depth' is nonzero; otherwise, if the
402 - return -EINVAL if 'power.disable_depth' is nonzero; otherwise, if the
404 or the device's usage_count is non-zero, increment the counter and
408 - decrement the device's usage counter
411 - decrement the device's usage counter; if the result is 0 then run
415 - decrement the device's usage counter; if the result is 0 then run
419 - decrement the device's usage counter; if the result is 0 then run
423 - decrement the device's usage counter; if the result is 0 then run
427 - decrement the device's usage counter; if the result is 0 then run
431 - decrement the device's 'power.disable_depth' field; if that field is equal
432 to zero, the runtime PM helper functions can execute subsystem-level
436 - increment the device's 'power.disable_depth' field (if the value of that
437 field was previously zero, this prevents subsystem-level runtime PM
441 necessary to execute the subsystem-level resume callback for the device
445 - check if there's a resume request pending for the device and resume it
449 necessary to execute the subsystem-level resume callback for the device to
453 - set/unset the power.ignore_children flag of the device
456 - clear the device's 'power.runtime_error' flag, set the device's runtime
464 - clear the device's 'power.runtime_error' flag, set the device's runtime
471 - return true if the device's runtime PM status is 'active' or its
475 - return true if the device's runtime PM status is 'suspended' and its
479 - return true if the device's runtime PM status is 'suspended'
482 - set the power.runtime_auto flag for the device and decrease its usage
487 - unset the power.runtime_auto flag for the device and increase its usage
492 - set the power.no_callbacks flag for the device and remove the runtime
497 - set the power.irq_safe flag for the device, causing the runtime-PM
501 - return true if power.irq_safe flag was set for the device, causing
502 the runtime-PM callbacks to be invoked with interrupts off
505 - set the power.last_busy field to the current time
508 - set the power.use_autosuspend flag, enabling autosuspend delays; call
513 - clear the power.use_autosuspend flag, disabling autosuspend delays;
518 - set the power.autosuspend_delay value to 'delay' (expressed in
527 - calculate the time when the current autosuspend delay period will expire,
530 nearest second; returns 0 if the delay period has already expired or
536 - pm_request_idle()
537 - pm_request_autosuspend()
538 - pm_schedule_suspend()
539 - pm_request_resume()
540 - pm_runtime_get_noresume()
541 - pm_runtime_get()
542 - pm_runtime_put_noidle()
543 - pm_runtime_put()
544 - pm_runtime_put_autosuspend()
545 - pm_runtime_enable()
546 - pm_suspend_ignore_children()
547 - pm_runtime_set_active()
548 - pm_runtime_set_suspended()
549 - pm_runtime_suspended()
550 - pm_runtime_mark_last_busy()
551 - pm_runtime_autosuspend_expiration()
556 - pm_runtime_idle()
557 - pm_runtime_suspend()
558 - pm_runtime_autosuspend()
559 - pm_runtime_resume()
560 - pm_runtime_get_sync()
561 - pm_runtime_put_sync()
562 - pm_runtime_put_sync_suspend()
563 - pm_runtime_put_sync_autosuspend()
570 -EAGAIN until pm_runtime_enable() is called for the device.
592 ->probe() callback will likely need to wake it up using one of the PM core's
603 It may be desirable to suspend the device once ->probe() has finished.
605 request to execute the subsystem-level idle callback for the device at that
606 time. A driver that makes use of the runtime autosuspend feature may want to
607 update the last busy mark before returning from ->probe().
618 calling pm_runtime_suspend() from their ->remove() routines, the driver core
621 drivers to make their ->remove() callbacks avoid races with runtime PM directly,
625 Drivers in ->remove() callback should undo the runtime PM changes done
626 in ->probe(). Usually this means calling pm_runtime_disable(),
645 as suspend-to-RAM and suspend-to-disk) interact with each other in a couple of
649 The device may have different wake-up settings for runtime PM and system sleep.
650 For example, remote wake-up may be enabled for runtime suspend but disallowed
652 the subsystem-level system suspend callback is responsible for changing the
653 device's wake-up setting (it may leave that to the device driver's system
662 * The device might need to switch power levels, wake-up settings, etc.
664 * Remote wake-up events might have been lost by the firmware.
679 to be updated to reflect the actual post-system sleep status. The way to do
682 - pm_runtime_disable(dev);
683 - pm_runtime_set_active(dev);
684 - pm_runtime_enable(dev);
687 ->suspend() callback and decrements it after calling the ->resume() callback.
690 following the return of the ->resume() callback, the ->runtime_idle() callback
694 or hardware operation. Instead, all hardware components are put into low-power
708 that the device appears to be runtime-suspended and its state is fine, so it
714 related to hibernation (see Documentation/driver-api/pm/devices.rst for more
722 right before executing the subsystem-level .prepare() callback for it and
724 subsystem-level .suspend() callback for it. In addition to that the PM core
726 device right before executing the subsystem-level .suspend_late() callback
730 every device right after executing the subsystem-level .resume_early()
731 callback and right after executing the subsystem-level .complete() callback
741 - invoke the ->runtime_suspend() callback provided by the driver of this
745 - invoke the ->runtime_resume() callback provided by the driver of this
749 - if the device has not been suspended at run time, invoke the ->suspend()
754 - if pm_runtime_suspended(dev) returns "false", invoke the ->suspend_noirq()
759 - invoke the ->resume() callback provided by the driver of this device and,
763 - invoke the ->resume_noirq() callback provided by the driver of this device
766 - if the device has not been suspended at run time, invoke the ->freeze()
771 - if pm_runtime_suspended(dev) returns "false", invoke the ->freeze_noirq()
776 - if the device has not been suspended at run time, invoke the ->thaw()
781 - if pm_runtime_suspended(dev) returns "false", invoke the ->thaw_noirq()
786 - if the device has not been suspended at run time, invoke the ->poweroff()
791 - if pm_runtime_suspended(dev) returns "false", run the ->poweroff_noirq()
796 - invoke the ->restore() callback provided by the driver of this device and,
800 - invoke the ->restore_noirq() callback provided by the device's driver
803 provide its own callbacks for ->runtime_idle(), ->runtime_suspend(),
804 ->runtime_resume(), ->suspend(), ->suspend_noirq(), ->resume(),
805 ->resume_noirq(), ->freeze(), ->freeze_noirq(), ->thaw(), ->thaw_noirq(),
806 ->poweroff(), ->poweroff_noirq(), ->restore(), ->restore_noirq() in the
807 subsystem-level dev_pm_ops structure.
815 8. "No-Callback" Devices
818 Some "devices" are only logical sub-devices of their parent and cannot be
819 power-managed on their own. (The prototype example is a USB interface. Entire
820 USB devices can go into low-power mode or send wake-up requests, but neither is
822 need of runtime PM callbacks; if the callbacks did exist, ->runtime_suspend()
823 and ->runtime_resume() would always return 0 without doing anything else and
824 ->runtime_idle() would always call pm_runtime_suspend().
830 prevent the non-debugging runtime PM sysfs attributes from being created.
833 ->runtime_idle(), ->runtime_suspend(), or ->runtime_resume() callbacks.
851 9. Autosuspend, or automatically-delayed suspends
855 A device should be put in a low-power state only when there's some reason to
859 at runtime until they have been inactive for some minimum period. Even when
860 the heuristic ends up being non-optimal, it will still prevent devices from
861 "bouncing" too rapidly between low-power and full-power states.
863 The term "autosuspend" is an historical remnant. It doesn't mean that the
866 automatically be delayed until the desired period of inactivity has elapsed.
871 of the inactivity period is a matter of policy. Subsystems can set this length
876 In order to use autosuspend, subsystems or drivers must call
879 instead of the non-autosuspend counterparts::
886 Drivers may also continue to use the non-autosuspend helper functions; they
887 will behave normally, which means sometimes taking the autosuspend delay into
892 autosuspend delay time has expired. If the ->runtime_suspend() callback
893 returns -EAGAIN or -EBUSY, and if the next autosuspend delay expiration time is
896 autosuspend. The ->runtime_suspend() callback can't do this rescheduling
902 synchronize ->runtime_suspend() callbacks with the arrival of I/O requests.
904 Here is a schematic pseudo-code example::
908 lock(&foo->private_lock);
910 if (foo->num_pending_requests++ == 0)
911 pm_runtime_get(&foo->dev);
912 if (!foo->is_suspended)
914 unlock(&foo->private_lock);
919 lock(&foo->private_lock);
920 if (--foo->num_pending_requests == 0) {
921 pm_runtime_mark_last_busy(&foo->dev);
922 pm_runtime_put_autosuspend(&foo->dev);
926 unlock(&foo->private_lock);
935 lock(&foo->private_lock);
936 if (foo->num_pending_requests > 0) {
937 ret = -EBUSY;
940 foo->is_suspended = 1;
942 unlock(&foo->private_lock);
950 lock(&foo->private_lock);
952 foo->is_suspended = 0;
953 pm_runtime_mark_last_busy(&foo->dev);
954 if (foo->num_pending_requests > 0)
956 unlock(&foo->private_lock);
960 The important point is that after foo_io_completion() asks for an autosuspend,
968 pm_runtime_autosuspend_expiration() from within the ->runtime_suspend()
971 -EAGAIN.