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authorRafael J. Wysocki <rjw@sisk.pl>2011-11-23 21:18:39 +0100
committerRafael J. Wysocki <rjw@sisk.pl>2011-11-28 22:14:19 +0100
commit5841eb6402707a387b216373e65c9c28e8136663 (patch)
tree1841f84c931e6e55ab510f4d44c505e802eae4eb /Documentation/power/runtime_pm.txt
parentbb58dd5d1ffad6c2d21c69698ba766dad4ae54e6 (diff)
PM / Domains: Document how PM domains are used by the PM core
The current power management documentation in Documentation/power/ either doesn't cover PM domains at all, or gives inaccurate information about them, so update the relevant files in there to follow the code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Diffstat (limited to 'Documentation/power/runtime_pm.txt')
-rw-r--r--Documentation/power/runtime_pm.txt29
1 files changed, 18 insertions, 11 deletions
diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 5336149f831b..79b10a090c9f 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -44,17 +44,24 @@ struct dev_pm_ops {
};
The ->runtime_suspend(), ->runtime_resume() and ->runtime_idle() callbacks
-are executed by the PM core for either the power domain, or the device type
-(if the device power domain's struct dev_pm_ops does not exist), or the class
-(if the device power domain's and type's struct dev_pm_ops object does not
-exist), or the bus type (if the device power domain's, type's and class'
-struct dev_pm_ops objects do not exist) of the given device, so the priority
-order of callbacks from high to low is that power domain callbacks, device
-type callbacks, class callbacks and bus type callbacks, and the high priority
-one will take precedence over low priority one. The bus type, device type and
-class callbacks are referred to as subsystem-level callbacks in what follows,
-and generally speaking, the power domain callbacks are used for representing
-power domains within a SoC.
+are executed by the PM core for the device's subsystem that may be either of
+the following:
+
+ 1. PM domain of the device, if the device's PM domain object, dev->pm_domain,
+ is present.
+
+ 2. Device type of the device, if both dev->type and dev->type->pm are present.
+
+ 3. Device class of the device, if both dev->class and dev->class->pm are
+ present.
+
+ 4. Bus type of the device, if both dev->bus and dev->bus->pm are present.
+
+The PM core always checks which callback to use in the order given above, so the
+priority order of callbacks from high to low is: PM domain, device type, class
+and bus type. Moreover, the high-priority one will always take precedence over
+a low-priority one. The PM domain, bus type, device type and class callbacks
+are referred to as subsystem-level callbacks in what follows.
By default, the callbacks are always invoked in process context with interrupts
enabled. However, subsystems can use the pm_runtime_irq_safe() helper function