Messages in this thread | | | From | Ulf Hansson <> | Date | Tue, 8 Jun 2021 16:30:48 +0200 | Subject | Re: [PATCH v2 3/3] PM: runtime: Clarify documentation when callbacks are unassigned |
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On Tue, 8 Jun 2021 at 16:23, Alan Stern <stern@rowland.harvard.edu> wrote: > > On Tue, Jun 08, 2021 at 11:02:50AM +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 v2: > > - Added a new patch for the updating the docs, as pointed out by Alan. > > > > --- > > Documentation/power/runtime_pm.rst | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/Documentation/power/runtime_pm.rst b/Documentation/power/runtime_pm.rst > > index 18ae21bf7f92..3d09c9fd450d 100644 > > --- a/Documentation/power/runtime_pm.rst > > +++ b/Documentation/power/runtime_pm.rst > > @@ -827,6 +827,14 @@ 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 manged > > +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. > > + > > You should also mention that if a callback pointer is NULL, the > runtime PM core will act as though there was a callback and it > returned 0. That's an important consideration.
Good point, let me add it.
I send a new version of $subject patch, unless Rafael is happy to do the amending when/if applying?
> > Also, notice that this file was carefully edited to make sure that > none of the lines exceed 80 characters. Your new addition should > be the same.
Absolutely, but it should be okay already, no?
> > Alan Stern
Kind regards Uffe
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