On Sun, 6 Dec 2009, Andreas Mohr wrote: > dynamic debugging of usb-serial behaviour of FTDI vs. pl2303 drivers > didn't show much, except for the fact that FTDI only has bulk in/out > endpoints, whereas pl2303 has an additional interrupt in endpoint. > (AHA!!) > > This might now indicate that interrupt-endpoint-less handling on > the receive side of things is broken, and possibly for this HC only > (ohci-ssb). > > I followed usb_submit_urb() down to urb_enqueue() and then finally > td_submit_urb(), but I don't know which kind of live debugging I'd have > to do to determine whether the HC driver does something incorrect or is > missing some setup. > And is there something that would help me on the userspace side of > things to figure out configuration status? (e.g. somewhere below > /sys/bus/usb...). > > Somehow I'm feeling pretty lost now... > > (the only idea that I currently still have is randomly plugging some > further devices to verify whether all non-interrupt devices lock up > and all interrupt ones work) You're grasping at straws. But if you want to indulge yourself, just about every USB drive uses bulk and not interrupt endpoints. Some may _have_ interrupt endpoints, because they are provided by the chip manufacturer, but they don't _use_ them. For a more productive debugging experience, get a usbmon trace of the failure, and afterwards see what's present in the debugging files in the appropriate subdirectory of /sys/kernel/debug/usb/ohci. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
