diff options
Diffstat (limited to 'Documentation/power/notifiers.txt')
| -rw-r--r-- | Documentation/power/notifiers.txt | 55 |
1 files changed, 0 insertions, 55 deletions
diff --git a/Documentation/power/notifiers.txt b/Documentation/power/notifiers.txt deleted file mode 100644 index a81fa254303d..000000000000 --- a/Documentation/power/notifiers.txt +++ /dev/null @@ -1,55 +0,0 @@ -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 . |