From 5841eb6402707a387b216373e65c9c28e8136663 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Wed, 23 Nov 2011 21:18:39 +0100 Subject: 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 --- Documentation/power/runtime_pm.txt | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) (limited to 'Documentation/power/runtime_pm.txt') 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 -- cgit v1.2.3