On Tuesday 17 November 2009, Mark Brown wrote: > On Tue, Nov 17, 2009 at 09:46:35PM +0900, Magnus Damm wrote: > > > On SuperH we have Runtime PM enabled on a few platforms together with > > a few updated drivers. The latest driver to become more power aware is > > this FSI driver. > > I understand exactly what the runtime PM stuff and the driver are doing > here, the issue is the mandatory suspend and resume functions. > > > At this point the SuperH specific platform bus code requires the > > callbacks ->runtime_suspend() and ->runtime_resume() to be present. It > > may be a good idea to allow them to be NULL in the future or maybe > > having some shared functions, but before starting to break out stuff > > I'd like to see how other Runtime PM implementations deal with this. > > So unless people object I prefer to keep it as-is for now. > > What is the reason for requiring that the driver provide stub functions? > For me the issue is that if it's mandatory for the driver to provide the > functions then having stub functions in there makes the driver look like > it is abusing the API by not implementing mandatory functionality. In fact, it's not mandatory for bus types, not for drivers. IMO bus types really have to know how to suspend a device and how to resume it, otherwise the core framework won't be useful anyway. What the bus type does about drivers not implementing ->runtime_suspend() or ->runtime_resume(), it's up to the bus type. That's even documented IIRC. Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
