On Thu, Feb 11, 2021 at 04:17:46PM -0500, Stephen L. Talbott wrote:
> 
> Is there an reason why a rather vanilla SL-7.9 system might report “4
> ports detected” on a new, Sabrent 7-port, powered USB 3.0 hub (HB-BUP7)?
>

Some of these usb switches have interesting internal structure (separate usb2
and usb3 hubs, two 4-port hubs cascaded from each other, etc) and the linux
usb hub driver may be confused and fail to enable all the ports.

You can see the bus structure that linux can see in the output
of "lsusb" and in /sys/bus/usb/devices/. There may be some error
messages in "dmesg" ("cannot enable port", etc).

And possibility of defective device cannot be ruled out,
these $1 products do not go through any QA.

Also if you have reports of device "HB-BUP7" working for somebody,
it means nothing. Makers of $1 USB devices are notorious
for shipping completeley different devices (different chips,
different linux drivers) under the same part number. Bait-and-switch
in action.

-- 
Konstantin Olchanski
Data Acquisition Systems: The Bytes Must Flow!
Email: olchansk-at-triumf-dot-ca
Snail mail: 4004 Wesbrook Mall, TRIUMF, Vancouver, B.C., V6T 2A3, Canada