[...]
> To debug USB related problems,
> you can start by compiling a new kernel with USB_DEBUG define then set
> the usbdebug to something different than 0 (depending on the verbosity
> you want/need). In this case since it's an ugen(4) related bug,
> defining UGEN_DEBUG also helps ;)
Thank you for the detailed explanation and pointers. Much appreciated.
> This diff simply remove the possibility to "unconfigure" a device by
> passing the magic value to usbd_set_config_no(). There's no code in
> our three that does that so it should be enough for the moment.
Configuration 0 should be the "unconfigured state" though according to
the libusb documentation some devices (not following the specification)
actually have a configuration 0. Not sure if that'd be an issue here.
Anyway, the patch below fixes the issue. Thanks again.
> Index: usb_subr.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/usb/usb_subr.c,v
> retrieving revision 1.96
> diff -u -p -r1.96 usb_subr.c
> --- usb_subr.c 15 Jan 2014 11:10:40 -0000 1.96
> +++ usb_subr.c 2 Feb 2014 17:05:43 -0000
> @@ -604,9 +604,6 @@ usbd_set_config_no(struct usbd_device *d
> usb_config_descriptor_t cd;
> usbd_status err;
>
> - if (no == USB_UNCONFIG_NO)
> - return (usbd_set_config_index(dev, USB_UNCONFIG_INDEX, msg));
> -
> DPRINTFN(5,("usbd_set_config_no: %d\n", no));
> /* Figure out what config index to use. */
> for (index = 0; index < dev->ddesc.bNumConfigurations; index++) {
