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    SubjectRe: 2.5.69 Interrupt Latency
    On Tue, 2003-05-13 at 10:26, Alan Stern wrote:

    > Putting in a sanity check for the global suspend state will be very easy.
    > But I would like to point out that this "global suspend" does not refer to
    > the entire system, only the USB bus.

    That is a problem then, because the delay can still
    occur during normal system operation.

    > I'm not sure under what
    > circumstances the bus is placed in global suspend; I think it's just when
    > there are no devices attached (or the last remaining device is detached).
    > However, there have been cases on my own system where turning off the only
    > USB peripheral caused the driver to bounce between suspend_hc() and
    > wakeup_hc() several times without any apparent explanation -- possibly as
    > a result of transient electrical signals on the bus (?). So perhaps
    > moving that delay out of the ISR isn't such a bad idea.

    Agreed. If this can happen on functional USB controllers
    when no devices are attached, then it is a serious problem.

    Paul Fulghum,
    Microgate Corporation,

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