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

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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
enabled earlier by calling pm_runtime_enable().
If the device bus type's or driver's ->probe() callback runs
pm_runtime_suspend() or pm_runtime_idle() or their asynchronous counterparts,
they will fail returning -EAGAIN, because the device's usage counter is
incremented by the driver core before executing ->probe(). Still, it may be
desirable to suspend the device as soon as ->probe() has finished, so the driver
core uses pm_runtime_put_sync() to invoke the subsystem-level idle callback for
the device at that time.
It may be desirable to suspend the device once ->probe() has finished.
Therefore the driver core uses the asyncronous pm_request_idle() to submit a
request to execute the subsystem-level idle callback for the device at that
time. A driver that makes use of the runtime autosuspend feature, may want to
update the last busy mark before returning from ->probe().
Moreover, the driver core prevents runtime PM callbacks from racing with the bus
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
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()
callback and right after executing the subsystem-level .resume() callback
for it, respectively.