[...] >>> > Say you want to leave the parent suspended after system resume, but the >>> > child drivers use pm_runtime_force_suspend|resume(). The parent would then >>> > need to use pm_runtime_force_suspend|resume() too, no? >>> >>> Actually no. >>> >>> Currently the other options of "deferring resume" (not using >>> pm_runtime_force_*), is either using the "direct_complete" path or >>> similar to the approach you took for the i2c designware driver. >>> >>> Both cases should play nicely in combination of a child being managed >>> by pm_runtime_force_*. That's because only when the parent device is >>> kept runtime suspended during system suspend, resuming can be >>> deferred. >> >> And because the parent remains in runtime suspend late enough in the >> system suspend path, its children also are guaranteed to be suspended. > > Yes. > >> >> But then all of them need to be left in runtime suspend during system >> resume too, which is somewhat restrictive, because some drivers may >> want their devices to be resumed then. > > Actually, this scenario is also addressed when using the pm_runtime_force_*. > > The driver for the child would only need to bump the runtime PM usage > count (pm_runtime_get_noresume()) before calling > pm_runtime_force_suspend() at system suspend. That then also > propagates to the parent, leading to that both the parent and the > child will be resumed when pm_runtime_force_resume() is called for > them. I need to correct myself here. The above currently only works if the child is runtime resumed while pm_runtime_force_suspend() is called. The logic in pm_runtime_force_* needs to be improved to take care of such scenarios. However I think that should be rather easy to fix, if we want that. [...] Kind regards Uffe
