On Thu, 2 Dec 2010, Ico wrote: > > Hello, > > We have a mips based custom board with ehci controller, which seem to > work just fine with some devices like memory sticks, but fails with > others like UMTS/HSDPA modems and HUB's. The host controller is not even > able to enumerate these devices, and after a few retries gives up. > > Symptoms include the message "device descriptor read/all, error -71", > more detailed kernel log and usbmon sniff are below. > > Because we suspected hardware issues we cut all USB traces from the PCB > and connected a USB host connector only a few mm from the USB pins of > the CPU, but still the same results. > > Any tips on how to proceed on debugging this ? You should use a bus analyzer to make sure the appropriate packets really are getting sent on the bus. Also test for analog noise. 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
