On Thursday, December 18, 2014 11:05:18 AM Sylwester Nawrocki wrote: > On 18/12/14 01:58, Rafael J. Wysocki wrote: > >>>> What's needed to solve this problem is a generalized way to have runtime > >>>> > >> PM dependencies between devices. Runtime PM already automatically > >>>> > >> handles parent devices as one type of dependent device (e.g. a parent > >>>> > >> device needs to be runtime PM resumed before its child.) So what's > >>>> > >> needed is a generic way to other PM dependencies with the runtime PM > >>>> > >> core (not the genpd core.) > >>> > > > >>> > > Considering the example above with three devices, device D1 and D2 are > >>> > > passive components in this power domain. These devices only need to > >>> > > know the state changes of the power domains but would not control the > >>> > > power domain themselves nor put forth constraints in the power domain > >>> > > state changes. So I did not clearly understand as to how this example > >>> > > could be solved by introducing changes in runtime PM core. > >> > > >> > Your solution only solves the problems for devices managed by genpd. > >> > > >> > If I understood your example correctly, what you really want to solve > >> > this problem more generically is to be able to tell the runtime PM core > >> > that D3 has a dependency on D1 and D2. Then, whenver the runtime PM > >> > core is doing get/put operations for D3, it needs to also do them for D1 > >> > and D2. > > Indeed, I think it would solve most of the problems if we were able to > model the PM dependencies between devices which would then be handled > in the PM core. I recall something like this has been proposed a while > ago [1]. Exactly. And I'm going to revive it in a slightly simplified form. > >> > This will accomplish the same as your proposed approach, but work for > >> > any devices in any PM domains. > > > > Plus, it is not limited to runtime PM, really. It affects system suspend > > too. > > [1] https://lkml.org/lkml/2009/8/26/485 > > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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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