On Mon, 2 May 2005, Glenn Maynard wrote: > The site closed for the day, and I was able to poke at it more actively. I > found a missing piece of the puzzle: if one of the lights is lit, the hub > flakes out as in the previous logs, and it works fine if not lit. EMI issue, > probably; it's a neon light. There are no visible problems with the USB hub > removed. > > So, the noise from the light screws up the USB hub; khubd keeps trying > to reinit it; and somewhere along the line, the I/O times out, too. The > code gets the timeout, closes the device and tries to reopen it, which > hangs (presumably due to khubd being busy trying to reinit that hub).
The two tasks should not interfere with one another, since the I/O board and the external hub are on different buses. The hang must have a different cause. > So the remaining question is--why is the I/O timing out? That didn't > happen with our last release, which used a 2.4 kernel (.26, I think). > If that doesn't happen, we never hit the enumeration locks and everything > (except for the USB hub--less important) continues to work. I'm not > sure how to diagnose further. Perhaps the IO times out because the EMI coming in to one host controller manages to affect the other one also. > If I comment out the debounce code entirely, the hub still flakes out, > but the IO device always keeps working (presumably this would cause flakiness > with other devices, but it does let me regain access to the device to > turn off the light and wake things back up). Maybe that's a hint. It sounds like hardware flakiness of one sort or another. The debouncing ends after a short time; after that you would expect things to behave the same as if the debouncing was commented out. Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by: NEC IT Guy Games. Get your fingers limbered up and give it your best shot. 4 great events, 4 opportunities to win big! Highest score wins.NEC IT Guy Games. Play to win an NEC 61 plasma display. Visit http://www.necitguy.com/?r=20 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
