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    SubjectRe: [PATCH] - race-free suspend. Was: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8)
    On Wed, 2 Jun 2010 10:50:39 +0200
    Florian Mickler <florian@mickler.org> wrote:

    > On Wed, 2 Jun 2010 18:06:14 +1000
    > Neil Brown <neilb@suse.de> wrote:
    >
    > > I cannot imagine why it would take multiple seconds to scan a keypad.
    > > Can you explain that?
    > >
    > > Do you mean while keys are held pressed? Maybe you don't get a wake-up event
    > > on key-release? In that case your user-space daemon could block suspend
    > > while there are any pressed keys.... confused.
    >
    > IIRC, the device sends interrupts only for first key-down and
    > last key-up.
    > To detect simultaneous key-presses you must actively scan it after the
    > first key-down.

    That makes sense - thanks.
    Presumably the first key-press gets to user-space promptly, so the user-space
    suspend daemon can be told not to suspend until the last key-up.

    Thanks,
    NeilBrown


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