On Tue, Nov 18, 2014 at 11:13:28AM -0500, Alan Stern wrote: > On Mon, 17 Nov 2014, Dmitry Torokhov wrote: > > > > > However, is it allowed to call pm_runtime_get_sync() on devices that > > > > didn't issue pm_runtime_enable()? > > > > > > Yes. But the bus has to issue pm_runtime_enable() before probing the > > > driver, because the driver will expect runtime PM to work properly > > > while its probe routine runs. For example, the probe routine might > > > want to leave the device in a runtime-suspended state. It can't do > > > that if the device isn't enabled for runtime PM. > > > > That means that runtime PM will be enabled for all devices on given bus > > while up till now drivers were deciding if their devices should be > > runtime-pm-managed or not. I do not think we are quite ready for this. > > It's up to both the bus _and_ the driver to make this decision. > > If a driver is completely runtime-PM-unaware then it will never > decrement the device's usage counter (which was incremented when the > bus called _get_noresume()), and therefore the device will never be > runtime-suspended. OK. Another question then: pm_runtime_get_noresume() does literally this: atomic_inc(&dev->power.usage_count); So who is responsible for actually waking up parent device and/or power domain? Is it simply missing because we did not really have PM domains before? Thanks. -- Dmitry -- 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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