Commit 4ec4f059 authored by Ulf Hansson's avatar Ulf Hansson Committed by Rafael J. Wysocki
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PM: runtime: Clarify documentation when callbacks are unassigned 



Recent changes to the PM core allows ->runtime_suspend|resume callbacks to
be unassigned.

In the earlier behaviour the PM core would return -ENOSYS, when trying to
runtime resume a device, for example. Let's update the documentation to
clarify this.

Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 63d00be6

Documentation/power/runtime_pm.rst

+9 −0
Original line number Diff line number Diff line
@@ -831,6 +831,15 @@ or driver about runtime power changes. Instead, the driver for the device's 
parent must take responsibility for telling the device's driver when the

parent's power state changes.



Note that, in some cases it may not be desirable for subsystems/drivers to call

pm_runtime_no_callbacks() for their devices. This could be because a subset of

the runtime PM callbacks needs to be implemented, a platform dependent PM

domain could get attached to the device or that the device is power managed

through a supplier device link. For these reasons and to avoid boilerplate code

in subsystems/drivers, the PM core allows runtime PM callbacks to be

unassigned. More precisely, if a callback pointer is NULL, the PM core will act

as though there was a callback and it returned 0.



9. Autosuspend, or automatically-delayed suspends

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