Messages in this thread | | | Date | Wed, 9 Jun 2021 10:16:23 -0400 | From | Alan Stern <> | Subject | Re: [PATCH v4 3/3] PM: runtime: Clarify documentation when callbacks are unassigned |
| |
On Wed, Jun 09, 2021 at 12:06:10PM +0200, Ulf Hansson wrote: > 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 > =================================================
Acked-by: Alan Stern <stern@rowland.harvard.edu>
I don't know what happened before. Maybe the terminal window got resized without me noticing, so the lines looked too long when they actually weren't.
Alan Stern
| |