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    SubjectRe: [linux-pm] [PATCH 0/8] Suspend block api (version 8)
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    On Thu, 2010-05-27 at 19:21 +0200, Florian Mickler wrote:
    > On Thu, 27 May 2010 18:45:25 +0200 (CEST)
    > Thomas Gleixner <tglx@linutronix.de> wrote:
    >
    > > The whole notion of treating suspend to RAM any different than a plain
    > > idle C-State is wrong. It's not different at all. You just use a
    > > different mechanism which has longer takedown and wakeup latencies and
    > > requires to shut down stuff and setup extra wakeup sources.
    > >
    > > And there is the whole problem. Switching from normal event delivery
    > > to those special wakeup sources. That needs to be engineered in any
    > > case carefuly and it does not matter whether you add suspend blockers
    > > or not.
    >
    > Ok, I just don't know the answer: How is it just another idle state if
    > the userspace gets frozen? Doesn't that bork the whole transition and
    > you need a userspace<->kernel synchronisation point to not loose events?

    There is no userspace to freeze when the runqueues are empty.

    And as explained, you won't loose events if all the devices do a proper
    state transition. To quote:

    On Thu, 2010-05-27 at 18:45 +0200, Thomas Gleixner wrote:
    > If the interrupt happens _BEFORE_ we switch over to the quiescent
    > state, then we need to backout. If it happens after the switch then it
    > goes into the nirwana if the suspend wakeup has not been set up
    > correctly. If we have it setup correctly then we go into suspend just
    > to come back immediately. There is nothing you can do about that with
    > suspend blockers.
    >



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