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authorYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 12:17:53 -0700
committerYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 15:44:42 -0700
commit9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch)
tree1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/power/notifiers.txt
parent98260f3884f4a202f9ca5eabed40b1354c489b29 (diff)
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
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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 .