diff options
| author | Ulf Hansson <ulf.hansson@linaro.org> | 2021-06-09 12:06:10 +0200 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2021-06-11 19:04:07 +0200 |
| commit | 4ec4f059088b48585c337328e05fa930c64d1ba8 (patch) | |
| tree | 63e4cc76e0df069ac1eed5c085e80f89158913b6 /Documentation/power | |
| parent | 63d00be69348fda431ae59aba6af268a5cf5058e (diff) | |
| download | lwn-4ec4f059088b48585c337328e05fa930c64d1ba8.tar.gz lwn-4ec4f059088b48585c337328e05fa930c64d1ba8.zip | |
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: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation/power')
| -rw-r--r-- | Documentation/power/runtime_pm.rst | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/power/runtime_pm.rst b/Documentation/power/runtime_pm.rst index b48cac5f9048..d6bf84f061f4 100644 --- a/Documentation/power/runtime_pm.rst +++ b/Documentation/power/runtime_pm.rst @@ -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 ================================================= |