On Tue, 27 Oct 2009, John Faith wrote: > >> and this is the usbmon dump around the "80 06" descriptor request and > >> the subsequent error -71 (EPROTO?): > >> > >> c671f8a0 1662538668 S Co:1:001:0 s 23 03 0004 0001 0000 0 > >> c671f8a0 1662538760 C Co:1:001:0 0 0 > >> c671f8a0 1662594851 S Ci:1:001:0 s a3 00 0000 0001 0004 4 < > >> c71ca140 1662594942 C Ii:1:001:1 0:2048 1 D > >> c71ca140 1662594973 S Ii:1:001:1 -115:2048 4 < > >> c671f8a0 1662595064 C Ci:1:001:0 0 4 = 03051200 > >> c671f8a0 1662657351 S Co:1:001:0 s 23 01 0014 0001 0000 0 > >> c671f8a0 1662657412 C Co:1:001:0 0 0 > >> c671f8a0 1662663393 S Ci:1:000:0 s 80 06 0100 0000 0040 64 < > >> c671f8a0 1662663485 C Ci:1:000:0 -71 0 > >> c671f8a0 1662663607 S Ci:1:000:0 s 80 06 0100 0000 0040 64 < > >> c671f8a0 1662663821 C Ci:1:000:0 -71 0 > >> > >> The same hub on an EVM board using the same kernel returns the > >> descriptor and works fine (can use USB mass storage), so I'm wondering > >> what type of failure this might indicate or how best to proceed. I > >> assume that the transceiver is mostly ok since some packets do make it > >> in and out before the descriptor request. > > > > They do? What packets are those? Certainly nothing in the extract > > above. > > I assumed that "S" and "C" before the descriptor request indicated > 2-way communication between the host controller and the hub based on > my minimal USB knowledge. Oh, okay. Your mixup is understandable. Look more closely at the device addresses in the usbmon output. The descriptor request was sent to device 000, which is your hub (before it has been assigned a real address). The earlier lines are addressed to device 001, which is the root hub -- a virtual device created by the controller driver and hardware. Messages sent to/from the root hub never appear as packets on the USB bus; they are internal to the host computer. > Is the descriptor request the first set of > bits that a hub might send? In other words, would a silent, > (damaged/non-transmitting) hub give similar usbmon output? Yes, exactly. Or a silent, damaged device of any kind, not necessarily a hub. 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
