On Wed, 29 Sep 2004, David Brownell wrote: > One thing Steve could do is show the equivalent level of > debug log output for UHCI-only, to see if the third reset > in a row also triggers disconnect. With UHCI-only, that > wouldn't switch to another HCD.
Steve, by this David means see what happens if you try doing "rmmod ehci-hcd" before plugging in the iPod. Post the debugging output you get with that scenario. > > I made khubd do a debounce for disconnects as well as for connects. > > That's why it shows up here; khubd thinks the iPod disconnected since > > UHCI told it so. > > Why debounce disconnects though? It'd just duplicate > debounce on the connect side, right? My reasoning was that a connect state change generally happens because the cable is physically being moved. That generates lots of transient signals, so it should be debounced regardless of direction (connect or disconnect). Yes, it's not really necessary for disconnects and it could be removed. > > Hard to tell, isn't it? From the log, it sure does look like the iPod > > actually did a soft disconnect. That's what the kernel thinks happened, > > anyway. > > I have a hard time believing it really disconnected though. > Not much point; and it just did a reset *without* disconnect; > mixing the two reset modes (with and without disconnect) > would just be wierd. And such a reset would make trouble > in some common configurations, so I can't imagine why > Apple would have coded such a thing. The difference is that the last time through the port was disabled, not reset. I can imagine the iPod handling that in a special way, particularly in the unaddressed or unconfigured state. > > > That "goes on and on" behavior is trouble, likely from one of > > > the recent khubd changes. I've seen similar trouble from > > > an RC2 kernel when an OHCI root hub port misbehaved ... > > > seems like disabling a port doesn't "stick" the way it used to. > > > > Or resetting the port causes EHCI to think a disconnect occurred... > > That'd be orthogonal to the "on and on" behavior change > I was describing. > > But if this iPod likes to disconnect after resets, that'd certainly > explain some of these problems. Thing is, I can't quite > imagine that's the issue ... else we'd have heard about > similar problems from lots of other iPod users, right? Well, I don't have any idea what the iPod was doing once EHCI got control of the port back from UHCI. But the log messages after each EHCI reset show a Connect-Status-Change followed by CSC plus Connect. That's why the "on and on" behavior occurred; the controller thinks the iPod disconnected and reconnected. Alan Stern ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
