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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-02-02 01:38:54 +0100
committerJonathan Corbet <corbet@lwn.net>2017-02-06 11:26:02 -0700
commit730c4c053012b058ccb5393bbc1691e4e872e741 (patch)
tree7998b44dc154c4e3389d832bbcbd905722a1b712 /Documentation/power/notifiers.txt
parent2728b2d2e5be4b828a523a06089cd605419fc65c (diff)
downloadlinux-730c4c053012b058ccb5393bbc1691e4e872e741.tar.gz
linux-730c4c053012b058ccb5393bbc1691e4e872e741.tar.xz
PM / sleep / docs: Convert PM notifiers document to reST
Move the document describing PM notifiers (used during system sleep state transitions) to Documentation/driver-api/pm/, convert it to reST and update it to use current terminology. Also replace the remaining references to the old version of it in .txt documents with references to the new one. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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-Suspend notifiers
- (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_HIBERNATION_PREPARE The system is going to hibernate, tasks will be frozen
- immediately. This is different from PM_SUSPEND_PREPARE
- below because here we do additional work between notifiers
- and drivers freezing.
-
-PM_POST_HIBERNATION The system memory state has been restored from a
- hibernation image or an error occurred during
- hibernation. Device drivers' restore callbacks have
- been executed and tasks have been thawed.
-
-PM_RESTORE_PREPARE The system is going to restore a hibernation image.
- If all goes well, the restored kernel will issue a
- PM_POST_HIBERNATION notification.
-
-PM_POST_RESTORE An error occurred during restore from hibernation.
- Device drivers' restore callbacks have been executed
- and tasks have been thawed.
-
-PM_SUSPEND_PREPARE The system is preparing for suspend.
-
-PM_POST_SUSPEND The system has just resumed or an error occurred during
- suspend. Device drivers' resume callbacks have been
- executed and tasks have been thawed.
-
-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 .