[CentOS] USB 2.0 device on a USB 3.0 plug
John R Pierce
pierce at hogranch.com
Thu Feb 16 20:28:22 UTC 2017
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
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