On 7 August 2015 at 14:19, Mark Brown <broonie@xxxxxxxxxx> wrote: > On Thu, Aug 06, 2015 at 04:11:39PM +0200, Tomeu Vizoso wrote: > >> Walks the OF tree up and finds the closest ancestor that has a platform >> device associated with it, probing it if isn't bound to a driver yet. > >> The above should ensure that the dependency represented by the passed OF >> node is available, because probing a platform device should cause its >> descendants to be probed as well. > > This sounds like it's going to break in the case where we have MFDs that > represent their functions in DT (not a pattern I'm a fan of but it's a > thing people do). We'll walk back to the platform device for the MFD > function, try to probe it and then give up. Perhaps that's good enough > anyway but it's not clear to me why we don't just try every parent we > find? Agreed. In the attempt at probing dependencies before a device is probed, I considered that a device's parent is also a dependency and that worked well. From what I saw, few devices will defer their probe if their parent hasn't been probed yet, assuming that it will have probed already. But with simple-mfd and simple-bus that shouldn't be relied upon as things will break if their parents defer their probe. With async probing enabled this failure scenario becomes more probable. > I'm also not a fan of the fact that the interface here is explicitly > saying that we want to probe a platform device, that's an implementation > detail that callers shouldn't need to know about. From the point of > view of the callers what they're trying to do is kick any dependencies > into being instantiated, the fact that we currently try to accomplish it > with platform devices isn't something they care about. Agreed. Thanks, Tomeu -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
