On Tue, Nov 17, 2009 at 9:59 PM, Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx> 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. Cool, but don't you think it makes sense to see how other architectures will deal with this first? >> 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. I see your point, but there is another side to it as well. Having the stubs there is a way of showing that these functions may be called as part of the Runtime PM management. Not having them would confuse people even more IMO. > Given that the arch is now dealing with clocking and power for the > device using the runtime PM system it seems fairly clear that there are > going to be drivers like this one that can at least skip the suspend > part and may not need to do anything at resume time either. Right. We just need to figure out what the arch-independent solution would be, and we're unfortunately not there yet. I can spend some time on updating the drivers and removing the nop-stubs if you'd like, but I'd rather not since I suspect that I'll have to update things again when we get Runtime PM for ARM or other non-sh architectures. Let me know what you think! / magnus _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
