On Mon, 25 Jan 2016, Doug Anderson wrote: > Hi, > > On Mon, Jan 25, 2016 at 1:51 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > On Mon, 25 Jan 2016, Peter Stuge wrote: > > > >> Alan Stern wrote: > >> > the device's embedded hub ACKs the packets from the PC and not the > >> > packets from the RPi. > >> > > >> > What other differences could there be? Timing? Power levels? > >> > >> Yes, both good candidates. Can you measure VUSB? > > > > Distinctly higher than 5V. > > > >> As for timing, the > >> host controller will send SOF more or less regularly, if too > >> irregular then that could cause problems for the device. Does your > >> analyzer provide precise timestamps? > > > > Yes, but the software doesn't want to display individual SOF packets. > > However I can see, for example, that 84 SOF packets were sent during a > > 10.3-ms period. Or 2048 were sent during a 256-ms period. It seems > > pretty regular. > > What analyzer are you using? The Total Phase Beagle 480, with their Data Center analysis software. 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
