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PM / Runtime: Update documentation around probe|remove|suspend 

PM core and driver core has changed some behavior regarding use of
runtime PM. Update the documentation accordingly.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Ulf Hansson 2013-11-08 06:13:51 +01:00 committed by Rafael J. Wysocki
parent baab52ded2
commit ea309944e2
1 changed files with 6 additions and 8 deletions
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14
Documentation/power/runtime_pm.txt
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@ -547,13 +547,11 @@ helper functions described in Section 4. In that case, pm_runtime_resume()
should be used. Of course, for this purpose the device's runtime PM has to be should be used. Of course, for this purpose the device's runtime PM has to be
enabled earlier by calling pm_runtime_enable(). enabled earlier by calling pm_runtime_enable().
If the device bus type's or driver's ->probe() callback runs It may be desirable to suspend the device once ->probe() has finished.
pm_runtime_suspend() or pm_runtime_idle() or their asynchronous counterparts, Therefore the driver core uses the asyncronous pm_request_idle() to submit a
they will fail returning -EAGAIN, because the device's usage counter is request to execute the subsystem-level idle callback for the device at that
incremented by the driver core before executing ->probe(). Still, it may be time. A driver that makes use of the runtime autosuspend feature, may want to
desirable to suspend the device as soon as ->probe() has finished, so the driver update the last busy mark before returning from ->probe().
core uses pm_runtime_put_sync() to invoke the subsystem-level idle callback for
the device at that time.
Moreover, the driver core prevents runtime PM callbacks from racing with the bus Moreover, the driver core prevents runtime PM callbacks from racing with the bus
notifier callback in __device_release_driver(), which is necessary, because the notifier callback in __device_release_driver(), which is necessary, because the
@ -656,7 +654,7 @@ out the following operations:
__pm_runtime_disable() with 'false' as the second argument for every device __pm_runtime_disable() with 'false' as the second argument for every device
right before executing the subsystem-level .suspend_late() callback for it. right before executing the subsystem-level .suspend_late() callback for it.
* During system resume it calls pm_runtime_enable() and pm_runtime_put_sync() * During system resume it calls pm_runtime_enable() and pm_runtime_put()
for every device right after executing the subsystem-level .resume_early() for every device right after executing the subsystem-level .resume_early()
callback and right after executing the subsystem-level .resume() callback callback and right after executing the subsystem-level .resume() callback
for it, respectively. for it, respectively.