Jetpack 4.3 and l4tbr0 bridge


are there some known issues/problem with the l4tbr0 bridge?
After flashing my custom bsp the l4tbr0 bridge is not recognized anymore.

With Jetpack 4.3.2 everything works fine!

Thanks for help

The l4tbr0 is related to the USB “gadget” which the development kit carrier board makes available on the micro-OTG USB port if a micro-B cable is inserted. The code is set up to make a virtual USB wired ethernet card appear to the host PC (and there are other uses too…for example, ignore mass storage).

If the USB portion of this fails, then I would expect the l4tbr0 to also fail. If the carrier board did not have the micro-OTG connector available with the exact same wiring layout as does your custom carrier board, then it is possible that either (a), the USB port cannot be used because the device tree and/or wiring is not valid for that hardware, or (b), the port works but something in the “gadget” software is looking for the wrong USB port.

You might want to examine the scripts/services in “/opt/nvidia/l4t-usb-mode/”, especially “”. Note that RNDIS is tied to USB and the bridge. Under “ifconfig” I would expect rndis0 to fail if usb0 is failed, and that l4tbr0 would itself then fail as only half of it would exist.

If you use a quality micro-B USB cable, and monitor “dmesg --follow” while the cable is connected to a host PC, do you see anything logged? Assuming the hardware is present, then there should be some output.