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linux/Documentation/power/notifiers.txt

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PM: introduce hibernation and suspend notifiers Make it possible to register hibernation and suspend notifiers, so that subsystems can perform hibernation-related or suspend-related operations that should not be carried out by device drivers' .suspend() and .resume() routines. [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: cleanups] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Cc: Nigel Cunningham <nigel@nigel.suspend2.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 16:47:36 +08:00
Suspend notifiers
PM: Allow drivers to allocate memory from .prepare() callbacks safely If device drivers allocate substantial amounts of memory (above 1 MB) in their hibernate .freeze() callbacks (or in their legacy suspend callbcks during hibernation), the subsequent creation of hibernate image may fail due to the lack of memory. This is the case, because the drivers' .freeze() callbacks are executed after the hibernate memory preallocation has been carried out and the preallocated amount of memory may be too small to cover the new driver allocations. Unfortunately, the drivers' .prepare() callbacks also are executed after the hibernate memory preallocation has completed, so they are not suitable for allocating additional memory either. Thus the only way a driver can safely allocate memory during hibernation is to use a hibernate/suspend notifier. However, the notifiers are called before the freezing of user space and the drivers wanting to use them for allocating additional memory may not know how much memory needs to be allocated at that point. To let device drivers overcome this difficulty rework the hibernation sequence so that the memory preallocation is carried out after the drivers' .prepare() callbacks have been executed, so that the .prepare() callbacks can be used for allocating additional memory to be used by the drivers' .freeze() callbacks. Update documentation to match the new behavior of the code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-18 05:26:00 +08:00
(C) 2007-2011 Rafael J. Wysocki <rjw@sisk.pl>, GPL
There are some operations that subsystems or drivers may want to carry out
before hibernation/suspend or after restore/resume, but they require the system
to be fully functional, so the drivers' and subsystems' .suspend() and .resume()
or even .prepare() and .complete() callbacks are not suitable for this purpose.
For example, device drivers may want to upload firmware to their devices after
resume/restore, but they cannot do it by calling request_firmware() from their
.resume() or .complete() routines (user land processes are frozen at these
points). The solution may be to load the firmware into memory before processes
are frozen and upload it from there in the .resume() routine.
A suspend/hibernation notifier may be used for this purpose.
The subsystems or drivers having such needs can register suspend notifiers that
will be called upon the following events by the PM core:
PM: introduce hibernation and suspend notifiers Make it possible to register hibernation and suspend notifiers, so that subsystems can perform hibernation-related or suspend-related operations that should not be carried out by device drivers' .suspend() and .resume() routines. [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: cleanups] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Cc: Nigel Cunningham <nigel@nigel.suspend2.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 16:47:36 +08:00
PM_HIBERNATION_PREPARE The system is going to hibernate or suspend, tasks will
be frozen immediately.
PM_POST_HIBERNATION The system memory state has been restored from a
PM: Allow drivers to allocate memory from .prepare() callbacks safely If device drivers allocate substantial amounts of memory (above 1 MB) in their hibernate .freeze() callbacks (or in their legacy suspend callbcks during hibernation), the subsequent creation of hibernate image may fail due to the lack of memory. This is the case, because the drivers' .freeze() callbacks are executed after the hibernate memory preallocation has been carried out and the preallocated amount of memory may be too small to cover the new driver allocations. Unfortunately, the drivers' .prepare() callbacks also are executed after the hibernate memory preallocation has completed, so they are not suitable for allocating additional memory either. Thus the only way a driver can safely allocate memory during hibernation is to use a hibernate/suspend notifier. However, the notifiers are called before the freezing of user space and the drivers wanting to use them for allocating additional memory may not know how much memory needs to be allocated at that point. To let device drivers overcome this difficulty rework the hibernation sequence so that the memory preallocation is carried out after the drivers' .prepare() callbacks have been executed, so that the .prepare() callbacks can be used for allocating additional memory to be used by the drivers' .freeze() callbacks. Update documentation to match the new behavior of the code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-18 05:26:00 +08:00
hibernation image or an error occurred during
hibernation. Device drivers' restore callbacks have
PM: introduce hibernation and suspend notifiers Make it possible to register hibernation and suspend notifiers, so that subsystems can perform hibernation-related or suspend-related operations that should not be carried out by device drivers' .suspend() and .resume() routines. [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: cleanups] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Cc: Nigel Cunningham <nigel@nigel.suspend2.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 16:47:36 +08:00
been executed and tasks have been thawed.
Hibernation: Add PM_RESTORE_PREPARE and PM_POST_RESTORE notifiers (rev. 2) Add PM_RESTORE_PREPARE and PM_POST_RESTORE notifiers to the PM core, to be used in analogy with the existing PM_HIBERNATION_PREPARE and PM_POST_HIBERNATION notifiers. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Len Brown <len.brown@intel.com>
2007-11-20 06:38:25 +08:00
PM_RESTORE_PREPARE The system is going to restore a hibernation image.
PM: Allow drivers to allocate memory from .prepare() callbacks safely If device drivers allocate substantial amounts of memory (above 1 MB) in their hibernate .freeze() callbacks (or in their legacy suspend callbcks during hibernation), the subsequent creation of hibernate image may fail due to the lack of memory. This is the case, because the drivers' .freeze() callbacks are executed after the hibernate memory preallocation has been carried out and the preallocated amount of memory may be too small to cover the new driver allocations. Unfortunately, the drivers' .prepare() callbacks also are executed after the hibernate memory preallocation has completed, so they are not suitable for allocating additional memory either. Thus the only way a driver can safely allocate memory during hibernation is to use a hibernate/suspend notifier. However, the notifiers are called before the freezing of user space and the drivers wanting to use them for allocating additional memory may not know how much memory needs to be allocated at that point. To let device drivers overcome this difficulty rework the hibernation sequence so that the memory preallocation is carried out after the drivers' .prepare() callbacks have been executed, so that the .prepare() callbacks can be used for allocating additional memory to be used by the drivers' .freeze() callbacks. Update documentation to match the new behavior of the code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-18 05:26:00 +08:00
If all goes well, the restored kernel will issue a
Hibernation: Add PM_RESTORE_PREPARE and PM_POST_RESTORE notifiers (rev. 2) Add PM_RESTORE_PREPARE and PM_POST_RESTORE notifiers to the PM core, to be used in analogy with the existing PM_HIBERNATION_PREPARE and PM_POST_HIBERNATION notifiers. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Len Brown <len.brown@intel.com>
2007-11-20 06:38:25 +08:00
PM_POST_HIBERNATION notification.
PM: Allow drivers to allocate memory from .prepare() callbacks safely If device drivers allocate substantial amounts of memory (above 1 MB) in their hibernate .freeze() callbacks (or in their legacy suspend callbcks during hibernation), the subsequent creation of hibernate image may fail due to the lack of memory. This is the case, because the drivers' .freeze() callbacks are executed after the hibernate memory preallocation has been carried out and the preallocated amount of memory may be too small to cover the new driver allocations. Unfortunately, the drivers' .prepare() callbacks also are executed after the hibernate memory preallocation has completed, so they are not suitable for allocating additional memory either. Thus the only way a driver can safely allocate memory during hibernation is to use a hibernate/suspend notifier. However, the notifiers are called before the freezing of user space and the drivers wanting to use them for allocating additional memory may not know how much memory needs to be allocated at that point. To let device drivers overcome this difficulty rework the hibernation sequence so that the memory preallocation is carried out after the drivers' .prepare() callbacks have been executed, so that the .prepare() callbacks can be used for allocating additional memory to be used by the drivers' .freeze() callbacks. Update documentation to match the new behavior of the code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-18 05:26:00 +08:00
PM_POST_RESTORE An error occurred during restore from hibernation.
Device drivers' restore callbacks have been executed
Hibernation: Add PM_RESTORE_PREPARE and PM_POST_RESTORE notifiers (rev. 2) Add PM_RESTORE_PREPARE and PM_POST_RESTORE notifiers to the PM core, to be used in analogy with the existing PM_HIBERNATION_PREPARE and PM_POST_HIBERNATION notifiers. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Len Brown <len.brown@intel.com>
2007-11-20 06:38:25 +08:00
and tasks have been thawed.
PM: Allow drivers to allocate memory from .prepare() callbacks safely If device drivers allocate substantial amounts of memory (above 1 MB) in their hibernate .freeze() callbacks (or in their legacy suspend callbcks during hibernation), the subsequent creation of hibernate image may fail due to the lack of memory. This is the case, because the drivers' .freeze() callbacks are executed after the hibernate memory preallocation has been carried out and the preallocated amount of memory may be too small to cover the new driver allocations. Unfortunately, the drivers' .prepare() callbacks also are executed after the hibernate memory preallocation has completed, so they are not suitable for allocating additional memory either. Thus the only way a driver can safely allocate memory during hibernation is to use a hibernate/suspend notifier. However, the notifiers are called before the freezing of user space and the drivers wanting to use them for allocating additional memory may not know how much memory needs to be allocated at that point. To let device drivers overcome this difficulty rework the hibernation sequence so that the memory preallocation is carried out after the drivers' .prepare() callbacks have been executed, so that the .prepare() callbacks can be used for allocating additional memory to be used by the drivers' .freeze() callbacks. Update documentation to match the new behavior of the code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-18 05:26:00 +08:00
PM_SUSPEND_PREPARE The system is preparing for suspend.
PM: introduce hibernation and suspend notifiers Make it possible to register hibernation and suspend notifiers, so that subsystems can perform hibernation-related or suspend-related operations that should not be carried out by device drivers' .suspend() and .resume() routines. [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: cleanups] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Cc: Nigel Cunningham <nigel@nigel.suspend2.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 16:47:36 +08:00
Fix common misspellings Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-31 09:57:33 +08:00
PM_POST_SUSPEND The system has just resumed or an error occurred during
PM: Allow drivers to allocate memory from .prepare() callbacks safely If device drivers allocate substantial amounts of memory (above 1 MB) in their hibernate .freeze() callbacks (or in their legacy suspend callbcks during hibernation), the subsequent creation of hibernate image may fail due to the lack of memory. This is the case, because the drivers' .freeze() callbacks are executed after the hibernate memory preallocation has been carried out and the preallocated amount of memory may be too small to cover the new driver allocations. Unfortunately, the drivers' .prepare() callbacks also are executed after the hibernate memory preallocation has completed, so they are not suitable for allocating additional memory either. Thus the only way a driver can safely allocate memory during hibernation is to use a hibernate/suspend notifier. However, the notifiers are called before the freezing of user space and the drivers wanting to use them for allocating additional memory may not know how much memory needs to be allocated at that point. To let device drivers overcome this difficulty rework the hibernation sequence so that the memory preallocation is carried out after the drivers' .prepare() callbacks have been executed, so that the .prepare() callbacks can be used for allocating additional memory to be used by the drivers' .freeze() callbacks. Update documentation to match the new behavior of the code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-18 05:26:00 +08:00
suspend. Device drivers' resume callbacks have been
executed and tasks have been thawed.
PM: introduce hibernation and suspend notifiers Make it possible to register hibernation and suspend notifiers, so that subsystems can perform hibernation-related or suspend-related operations that should not be carried out by device drivers' .suspend() and .resume() routines. [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: cleanups] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Cc: Nigel Cunningham <nigel@nigel.suspend2.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 16:47:36 +08:00
It is generally assumed that whatever the notifiers do for
PM_HIBERNATION_PREPARE, should be undone for PM_POST_HIBERNATION. Analogously,
operations performed for PM_SUSPEND_PREPARE should be reversed for
PM_POST_SUSPEND. Additionally, all of the notifiers are called for
PM_POST_HIBERNATION if one of them fails for PM_HIBERNATION_PREPARE, and
all of the notifiers are called for PM_POST_SUSPEND if one of them fails for
PM_SUSPEND_PREPARE.
The hibernation and suspend notifiers are called with pm_mutex held. They are
defined in the usual way, but their last argument is meaningless (it is always
NULL). To register and/or unregister a suspend notifier use the functions
register_pm_notifier() and unregister_pm_notifier(), respectively, defined in
include/linux/suspend.h . If you don't need to unregister the notifier, you can
also use the pm_notifier() macro defined in include/linux/suspend.h .