Re: Runtime PM: Calling Device runtime PM callbacks?

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Monday 14 December 2009, Alan Stern wrote:
> On Mon, 14 Dec 2009, Mahalingam, Nithish wrote:
> 
> > I had one more question -
> > 
> > +The ->runtime_suspend() callback is executed by the PM core for the bus type,
> > +device type and device class of the device being suspended.  The bus type,
> > +device type and device class callbacks are then _entirely_ _responsible_ for
> > +handling the device as appropriate, which may, but need not include executing
> > +the device driver's own ->runtime_suspend() callback (from the PM core's point
> > +of view it is not necessary to implement a ->runtime_suspend() callback in a
> > +device driver as long as the bus type, device type and device class
> > +->runtime_suspend() know what to do to handle the device).
> > 
> > Any specific reason why from PM core we should not call the device driver's 
> > ->runtime_suspend() or ->runtime_resume()? I know one of either the bus/
> > class/type should implement device suspend but what if (worst case) none of 
> > them are doing it? Is it OK in that case (alone) to call device driver's 
> > runtime PM directly (if it is implemented) from the runtime PM core?
> 
> The system PM driver_suspend() and driver_resume() routines don't do 
> that.  For consistency, the runtime PM routines should behave the same 
> way.
> 
> Alan Stern
> 
> P.S.: Rafael, I just realized that your documentation changes could be
> reduced considerably.  All you have to do is explain once how whenever
> a method call occurs, the PM core will search for a callback pointer in
> the following locations: ...  Then in all those places where you list
> all the callback possibilities, just say "the callback routine" or
> something like that.

Yeah.  It was late yesterday when I was preparing the patch and I just didn't
think about that.

Rafael