2

I'm running Ubuntu 18.04 on a Lenovo Carbon X1 5th, 2017 model.

A Lenovo P27u display, containing an integrated USB-3 hub with three USB-3 connectors (blue) is connected via USB-C (also used as power supply) to the laptop. I can use an i-tec USB-3 with an integrated Ethernet adapter without problems when I connect it directly to my laptop: It shows up as two USB devices:

Bus 002 Device 013: ID 0bda:8153 Realtek Semiconductor Corp. 
Bus 002 Device 012: ID 2109:0813 VIA Labs, Inc. 

However, when I plug the i-tec USB3 hub into one of the USB ports of my Lenovo P27u display I only see the USB hub device (VIA Labs, Inc.) but the integrated Ethernet adapter in the i-tec USB3 hub doesn't show up in lsusb nor in ifconfig (naturally...).

In lack of other hardware, I can not directly test, if this is related specifically to the display or if this is a problem, when connecting such adapters after another hub in general.

I also tried to install the Realtek 8152 driver from their webpage, which did not change anything.

Any ideas how to tackle this problem? Does anybody have similar hardware to troubleshoot this issue?

Note: On the Display hub is a fourth connector colored in yellow, where opinions seem to disagree, if this is for charging only, but I'm not talking about that one.

Note II: I figured out another part of this issue: The on-screen menu of the display has an option called "USB Select", which can be set to either USB2 or USB3. If set to USB, the USB + ETH adapter also works on any of the "regular" i.e. non-yellow USB3 ports on the display. I did not try all possible combinations of settings though.

  • Can you be a bit more verbose where all the USB ports are what type they are and what "it" is? The USB hub or the Ethernet adapter? Now it looks like the USB ports on your screen are not USB3, so a hardware problem. – Fabby May 17 '18 at 4:39
  • I did modify the question to reflect your comment. The USB ports on the screen should be USB3. – engineer May 18 '18 at 6:58
1

This problem has existed since USB-1: The i-tec USB-C Slim Passive HUB 3 Port + Gigabit Ethernet Adapter is a passive hub and I've noticed over the years that active hubs don't have this problem, but passive hubs do: they need to distribute the power they get from a single USB port over their own USB ports, so they shut down the added peripherals or the main hub's port just doesn't have enough juice to power the power-hungry peripherals.

E.G. an SD-Card reader with an integrated hub does the same issue so the rule of thumb for USB hubs is: don't plug hubs or peripherals needing a lot of power into another hub but straight into the computer.

Having said that:

  • plugging in low-powered peripherals like a mouse into the port of a hub of a hub will work,
  • some HDDs won't power on unless inserted into a high-power port of the hub (and definitely not into a port of a hub of a hub.): In your case: plug the adapter into the high-power yellow USB Port.

¯\_(ツ)_/¯

  • 1
    Thank you for this answer! Actually I got it to work now with a hint of yours. If you connect the hub + ethernet adapter to this yellow-colored USB port on the monitor that is supposed to be used for charging devices, it works. So it really seems to be a matter of power consumption or power saving profiles within the hub. – engineer May 18 '18 at 9:43
  • Updated answer, good hunting! +1 to question. (Had a lot of work figuring out what your problem was ;- – Fabby May 18 '18 at 12:03
  • 1
    Thank you for doing the dirty work to rewrite the question! – engineer May 18 '18 at 13:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.