Messages in this thread Patch in this message | | | From | Ulf Hansson <> | Subject | [PATCH v4 3/3] PM: runtime: Clarify documentation when callbacks are unassigned | Date | Wed, 9 Jun 2021 12:06:10 +0200 |
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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: Ulf Hansson <ulf.hansson@linaro.org> ---
Changes in v4: - This time, really, fix spelling and further clarified the behaviour, according to comments from Alan.
--- Documentation/power/runtime_pm.rst | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/Documentation/power/runtime_pm.rst b/Documentation/power/runtime_pm.rst index 18ae21bf7f92..8a0a43811e3a 100644 --- a/Documentation/power/runtime_pm.rst +++ b/Documentation/power/runtime_pm.rst @@ -827,6 +827,15 @@ 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 ================================================= -- 2.25.1
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