Bumping after 19 hours on Saturday is a bit hasty.
What’s the logic level voltage you need? Do you have a level shifter? I think the Jetson’s UART is 1.8V.
If your logic levels match, then I think you can try using one of the /dev/ttyTHSx devices. I don’t know which one (if any) matches the pins you mentioned though. Checking the schematics and the pinmux should clarify that.
I’m using UART RX/TX 0 which is mapped to /dev/ttyTHS0. I’m guessing RX/TX 2 is mapped to /dev/ttyTHS2. I didn’t have to add anything to the kernel (using Grinch 21.2.1).
Using it is really straight forward. You can easily find an example for any language, and it should work just by replacing the path to ttyTHx.
Check termios.h manual page if you’re looking to work in C.
You can see a smashing video of the the UART in action (along with level shifting) here:
This thread has been open for a long time, unfortunately I just got around to playing with the UARTs. I’m sure the posters have long since solved the problem and moved on, this answer is here informational purposes.