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authorLinus Torvalds <torvalds@linux-foundation.org>2012-01-08 13:10:57 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-08 13:10:57 -0800
commiteb59c505f8a5906ad2e053d14fab50eb8574fd6f (patch)
treec6e875adc12b481b916e847e8f80b8881a0fb02c /Documentation/power/devices.txt
parent1619ed8f60959829d070d8f39cd2f8ca0e7135ce (diff)
parentc233523b3d392e530033a7587d7970dc62a02361 (diff)
downloadop-kernel-dev-eb59c505f8a5906ad2e053d14fab50eb8574fd6f.zip
op-kernel-dev-eb59c505f8a5906ad2e053d14fab50eb8574fd6f.tar.gz
Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
* 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (76 commits) PM / Hibernate: Implement compat_ioctl for /dev/snapshot PM / Freezer: fix return value of freezable_schedule_timeout_killable() PM / shmobile: Allow the A4R domain to be turned off at run time PM / input / touchscreen: Make st1232 use device PM QoS constraints PM / QoS: Introduce dev_pm_qos_add_ancestor_request() PM / shmobile: Remove the stay_on flag from SH7372's PM domains PM / shmobile: Don't include SH7372's INTCS in syscore suspend/resume PM / shmobile: Add support for the sh7372 A4S power domain / sleep mode PM: Drop generic_subsys_pm_ops PM / Sleep: Remove forward-only callbacks from AMBA bus type PM / Sleep: Remove forward-only callbacks from platform bus type PM: Run the driver callback directly if the subsystem one is not there PM / Sleep: Make pm_op() and pm_noirq_op() return callback pointers PM/Devfreq: Add Exynos4-bus device DVFS driver for Exynos4210/4212/4412. PM / Sleep: Merge internal functions in generic_ops.c PM / Sleep: Simplify generic system suspend callbacks PM / Hibernate: Remove deprecated hibernation snapshot ioctls PM / Sleep: Fix freezer failures due to racy usermodehelper_is_disabled() ARM: S3C64XX: Implement basic power domain support PM / shmobile: Use common always on power domain governor ... Fix up trivial conflict in fs/xfs/xfs_buf.c due to removal of unused XBT_FORCE_SLEEP bit
Diffstat (limited to 'Documentation/power/devices.txt')
-rw-r--r--Documentation/power/devices.txt37
1 files changed, 21 insertions, 16 deletions
diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt
index 3139fb5..20af7de 100644
--- a/Documentation/power/devices.txt
+++ b/Documentation/power/devices.txt
@@ -126,7 +126,9 @@ The core methods to suspend and resume devices reside in struct dev_pm_ops
pointed to by the ops member of struct dev_pm_domain, or by the pm member of
struct bus_type, struct device_type and struct class. They are mostly of
interest to the people writing infrastructure for platforms and buses, like PCI
-or USB, or device type and device class drivers.
+or USB, or device type and device class drivers. They also are relevant to the
+writers of device drivers whose subsystems (PM domains, device types, device
+classes and bus types) don't provide all power management methods.
Bus drivers implement these methods as appropriate for the hardware and the
drivers using it; PCI works differently from USB, and so on. Not many people
@@ -268,32 +270,35 @@ various phases always run after tasks have been frozen and before they are
unfrozen. Furthermore, the *_noirq phases run at a time when IRQ handlers have
been disabled (except for those marked with the IRQF_NO_SUSPEND flag).
-All phases use PM domain, bus, type, or class callbacks (that is, methods
-defined in dev->pm_domain->ops, dev->bus->pm, dev->type->pm, or dev->class->pm).
-These callbacks are regarded by the PM core as mutually exclusive. Moreover,
-PM domain callbacks always take precedence over bus, type and class callbacks,
-while type callbacks take precedence over bus and class callbacks, and class
-callbacks take precedence over bus callbacks. To be precise, the following
-rules are used to determine which callback to execute in the given phase:
+All phases use PM domain, bus, type, class or driver callbacks (that is, methods
+defined in dev->pm_domain->ops, dev->bus->pm, dev->type->pm, dev->class->pm or
+dev->driver->pm). These callbacks are regarded by the PM core as mutually
+exclusive. Moreover, PM domain callbacks always take precedence over all of the
+other callbacks and, for example, type callbacks take precedence over bus, class
+and driver callbacks. To be precise, the following rules are used to determine
+which callback to execute in the given phase:
- 1. If dev->pm_domain is present, the PM core will attempt to execute the
- callback included in dev->pm_domain->ops. If that callback is not
- present, no action will be carried out for the given device.
+ 1. If dev->pm_domain is present, the PM core will choose the callback
+ included in dev->pm_domain->ops for execution
2. Otherwise, if both dev->type and dev->type->pm are present, the callback
- included in dev->type->pm will be executed.
+ included in dev->type->pm will be chosen for execution.
3. Otherwise, if both dev->class and dev->class->pm are present, the
- callback included in dev->class->pm will be executed.
+ callback included in dev->class->pm will be chosen for execution.
4. Otherwise, if both dev->bus and dev->bus->pm are present, the callback
- included in dev->bus->pm will be executed.
+ included in dev->bus->pm will be chosen for execution.
This allows PM domains and device types to override callbacks provided by bus
types or device classes if necessary.
-These callbacks may in turn invoke device- or driver-specific methods stored in
-dev->driver->pm, but they don't have to.
+The PM domain, type, class and bus callbacks may in turn invoke device- or
+driver-specific methods stored in dev->driver->pm, but they don't have to do
+that.
+
+If the subsystem callback chosen for execution is not present, the PM core will
+execute the corresponding method from dev->driver->pm instead if there is one.
Entering System Suspend
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