From ea309944e226d655d7d4adca9623c575ba786bbe Mon Sep 17 00:00:00 2001 From: Ulf Hansson Date: Fri, 8 Nov 2013 06:13:51 +0100 Subject: 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 Signed-off-by: Rafael J. Wysocki --- Documentation/power/runtime_pm.txt | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) (limited to 'Documentation/power/runtime_pm.txt') diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt index 0f54333b0ff2..b6ce00b2be9a 100644 --- a/Documentation/power/runtime_pm.txt +++ b/Documentation/power/runtime_pm.txt @@ -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. -- cgit v1.2.3-59-g8ed1b