On Mon, 17 Nov 2014, Dmitry Torokhov wrote: > > For devices that aren't part of a power domain, things are simpler. > > The bus does _get_noresume() to make sure the device won't be runtime > > suspended while the probe routine is running. It doesn't do > > _get_sync(), because that would end up calling the driver's > > runtime_resume routine before the driver was bound to the device. (The > > bus could prevent that from happening by taking special precautions, > > like PCI does, but in general it's a nuisance.) > > That's why I think we need some new call that would mean "make sure the > device is powered" which would properly handle power domain and bus, but > ignore all driver stuff since it may not be initialized yet. And similar > call for asking to put device and maybe domain in powered down state in > case probing failed. I can't imagine how such a call would work. The PM core invokes the subsystem's runtime_suspend/resume callback, and then the subsystem's routine is responsible for invoking the driver's callback (or _not_ invoking it, in this case). Thus, the PM core has no way to tell the subsystem's callback not to invoke the driver's routine, and adding a new runtime PM call wouldn't change that. You'd have to add a new pair of callbacks instead, which IMO would be a tremendous waste. Furthermore, the subsystem already _knows_ when the driver gets probed, because probing works in the same sort of way: The subsystem's probe routine gets invoked, and it is responsible for invoking the driver's probe routine. Therefore the PM core doesn't _need_ to provide this extra information to the subsystem. Rather, the subsystem just needs to keep track of the information it already has available. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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