[LAU] Repeated USB error/warning notification

Chris Caudle chris at chriscaudle.org
Tue May 22 21:30:35 CEST 2018

On Tue, May 22, 2018 1:05 pm, Jeanette C. wrote:
> I wonder: could it be that the USB hub can't transmit/receive data fast
> enough? It has a USB typing keyboard and a Braille display connected,
> which take energy from it and the MIDI keyboard, which is externally
> powered.

I have not seen this situation in quite a while, but if a slow device is
actually a USB 1.1 device, and not a USB 2 device running at slow speed,
all the devices on the hub will have to run at USB 1 speeds.

There also seems to be a difference between some high speed USB 2 hubs,
which can either have a single speed translator that is shared between all
low and full speed devices to translate to the upstream high speed port,
or may have multiple, up to one per downstream port.

So it may be possible that the typing keyboard and/or the Braille display
is causing some problems if  one of them is old enough to be a USB 1
device.  Capturing the output of lsusb -t should show that.

Chris C

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