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#1 2020-08-03 10:46:13

minifridge
Member
Registered: 2020-06-21
Posts: 4

Dell TB16 drops usb connection

I have problems with USB devices dropouts in my docking station.

My configuration is as follows:

Dell TB16 that is hooked into a Dell XPS 9570 laptop. Both laptop and dock are up to the latest firmware.

The TB16 is quite loaded with peripherals:

  • Gigabit Ethernet

  • external USB audio interface with external power

  • 4k 60hz over displayport

  • USB 3.0 hub with external power connected to a laser wireless mouse, a keyboard and a microsoft webcam

Quite frequently, my mouse, and sometimes my keyboard drops connection drops out. As far as I can see no kernel log failure is visible. To get them working again is to unplug and plug it back.

I have not found a way to reproduce this behavior reliably but I have noticed a pattern with video-call software, when video starts mouse almost always connection drops immediately and re drops if connected again. The workaround is mouseless meetings or plugging the mouse on the laptop usb port which works flawlessly.

This hints me to bad combination of drivers failing under load? The wireless mouse is a cheap Chinese one with high-dpi sensor. I have not tried combination of other hardware to reproduce the issue but none of the listed hardware gave me problems outside the TB16 docking station.

After digging around i found this comment which describes to a large extend the behavior I am experiencing.

Are there some kernel settings I can tweak to avoid this behavior?

Also can I do a soft rescan of the usb bus to re-enroll again the failed device?

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#2 2020-08-04 09:30:49

wevie
Member
Registered: 2020-08-04
Posts: 1

Re: Dell TB16 drops usb connection

I can confirm this behavior; my 9570 and TB16 are connected behind a KVM switch which is regularly switching between connected systems.
Activating the 9570 / TB16 most of the times drops the connection to the connected USB devices. Connected DP and HDMI monitors often also don't come back online.

Seems that our Ubuntu colleagues have released a couple of fixex related to this behavior?
https://bugs.launchpad.net/ubuntu/+sour … ug/1855312
https://lore.kernel.org/linux-usb/20191 … cal.com/T/

Those fixes (workarounds..?) don't seem to be included in the mainline kernel (yet).

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