On 2/16/2017 9:58 AM, Jerry Geis wrote: > When I plug in my device which is USB 2.0 into a 3.0 slot (cause that is > all I have) > [495042.943074] usb 5-2: new low-speed USB device number 6 using xhci_hcd > [495043.100076] usb 5-2: device descriptor read/64, error -71 > > I receive the above error. > > Is there a flag or setting that tells the USB to in a 2.0 mode ? USB 1 and 2 used 4 pins. USB 3 ports have an ADDITIONAL 5 pins, the original 4 are used for USB 1/2 operation, the new 5 only for USB 3 operation. they are effectively two completely independent controllers. the combined protocol stack is an unholy mess of poorly planned extensions. -- john r pierce, recycling bits in santa cruz