Messages in this thread | | | Subject | Re: 2.5.69 Interrupt Latency | From | Paul Fulghum <> | Date | 13 May 2003 10:35:07 -0500 |
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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, paulkf@microgate.com Microgate Corporation, http://www.microgate.com
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