On Sun, 10 Jul 2005, Valentijn Sessink wrote: > Hello all, > > I'm having problems with a sn9c102 webcam. > > - it works when directly attached to the PC > - it doesn't work when attached to an external USB hub > - it does work again when I remove ehci-hcd
> Opening the camera device will work now, but I can't get any images and the > driver seems "stuck" in some way - I cannot even close the fd afterwards, > and hotplug starts to behave strangely afterwards (which isn't that strange, > considering that I try to remove and reinsert a busy device with a driver in > unknown state). > > What could I do next to find out what's wrong? Do you know if the camera uses isochronous transfers? You can tell if there are any iso endpoints by looking at the camera's entry in /proc/bus/usb/devices. The symptoms you described are typical for IN iso transfers. The ehci-hcd driver has incomplete support for such transfers when they come from a full-speed device attached via a high-speed hub. The work-arounds are: attach the device directly to the PC (as you know), rmmod ehci-hcd (as you know), or use a USB 1.1 hub instead of a USB 2.0 hub. Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by the 'Do More With Dual!' webinar happening July 14 at 8am PDT/11am EDT. We invite you to explore the latest in dual core and dual graphics technology at this free one hour event hosted by HP, AMD, and NVIDIA. To register visit http://www.hp.com/go/dualwebinar _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
