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    SubjectRe: [patch update] Re: [linux-pm] Run-time PM idea (was: Re: [RFC][PATCH 0/2] PM: Rearrange core suspend code)
    Am Mittwoch, 10. Juni 2009 21:27:56 schrieb Rafael J. Wysocki:
    > > What happens if the parent's parent is also suspended? It seems to me
    > > that you must code this recursively.
    > Hmm, I thought I did.
    > [Looks]
    > pm_request_resume(dev) will call pm_request_resume(dev->parent), if
    > necessary, and that will call pm_request_resume(dev->parent->parent) and so
    > on.  Each of them will queue a work item and the one for the topmost parent
    > will be queued first.  So, the resume requests for all parents will be
    > executed before the one for the device, due to the fact that the workqueue
    > is singlethread.

    Sneaky, I overlooked that.

    > Well, there is a bug related to it, namely pm_autosuspend() may change the
    > status to RPM_SUSPENDED after pm_request_resume() has changed it to
    > RPM_WAKE, that needs fixing.

    Ok, maybe this is related. You recurse if the parent isn't in RPM_ACTIVE.
    But that is not enough. You must ensure that all the nodes higher up stay
    in RPM_ACTIVE. It seems to me that you must go up until you find an
    active node (or the root) and put it a blocked state.


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