diff options
Diffstat (limited to 'Documentation/power/runtime_pm.txt')
| -rw-r--r-- | Documentation/power/runtime_pm.txt | 48 |
1 files changed, 40 insertions, 8 deletions
diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt index 489e9bacd165..654097b130b4 100644 --- a/Documentation/power/runtime_pm.txt +++ b/Documentation/power/runtime_pm.txt @@ -1,6 +1,6 @@ Run-time Power Management Framework for I/O Devices -(C) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc. +(C) 2009-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc. (C) 2010 Alan Stern <stern@rowland.harvard.edu> 1. Introduction @@ -44,11 +44,21 @@ struct dev_pm_ops { }; The ->runtime_suspend(), ->runtime_resume() and ->runtime_idle() callbacks are -executed by the PM core for either the bus type, or device type (if the bus -type's callback is not defined), or device class (if the bus type's and device -type's callbacks are not defined) of given device. The bus type, device type -and device class callbacks are referred to as subsystem-level callbacks in what -follows. +executed by the PM core for either the device type, or the class (if the device +type's struct dev_pm_ops object does not exist), or the bus type (if the +device type's and class' struct dev_pm_ops objects do not exist) of the given +device (this allows device types to override callbacks provided by bus types or +classes if necessary). The 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 +to tell the PM core that a device's ->runtime_suspend() and ->runtime_resume() +callbacks should be invoked in atomic context with interrupts disabled +(->runtime_idle() is still invoked the default way). This implies that these +callback routines must not block or sleep, but it also means that the +synchronous helper functions listed at the end of Section 4 can be used within +an interrupt handler or in an atomic context. The subsystem-level suspend callback is _entirely_ _responsible_ for handling the suspend of the device as appropriate, which may, but need not include @@ -237,6 +247,10 @@ defined in include/linux/pm.h: Section 8); it may be modified only by the pm_runtime_no_callbacks() helper function + unsigned int irq_safe; + - indicates that the ->runtime_suspend() and ->runtime_resume() callbacks + will be invoked with the spinlock held and interrupts disabled + unsigned int use_autosuspend; - indicates that the device's driver supports delayed autosuspend (see Section 9); it may be modified only by the @@ -344,6 +358,10 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: - decrement the device's usage counter; if the result is 0 then run pm_runtime_idle(dev) and return its result + int pm_runtime_put_sync_suspend(struct device *dev); + - decrement the device's usage counter; if the result is 0 then run + pm_runtime_suspend(dev) and return its result + int pm_runtime_put_sync_autosuspend(struct device *dev); - decrement the device's usage counter; if the result is 0 then run pm_runtime_autosuspend(dev) and return its result @@ -379,8 +397,8 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: zero) bool pm_runtime_suspended(struct device *dev); - - return true if the device's runtime PM status is 'suspended', or false - otherwise + - return true if the device's runtime PM status is 'suspended' and its + 'power.disable_depth' field is equal to zero, or false otherwise void pm_runtime_allow(struct device *dev); - set the power.runtime_auto flag for the device and decrease its usage @@ -397,6 +415,11 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: PM attributes from /sys/devices/.../power (or prevent them from being added when the device is registered) + void pm_runtime_irq_safe(struct device *dev); + - set the power.irq_safe flag for the device, causing the runtime-PM + suspend and resume callbacks (but not the idle callback) to be invoked + with interrupts disabled + void pm_runtime_mark_last_busy(struct device *dev); - set the power.last_busy field to the current time @@ -438,6 +461,15 @@ pm_runtime_suspended() pm_runtime_mark_last_busy() pm_runtime_autosuspend_expiration() +If pm_runtime_irq_safe() has been called for a device then the following helper +functions may also be used in interrupt context: + +pm_runtime_suspend() +pm_runtime_autosuspend() +pm_runtime_resume() +pm_runtime_get_sync() +pm_runtime_put_sync_suspend() + 5. Run-time PM Initialization, Device Probing and Removal Initially, the run-time PM is disabled for all devices, which means that the |