ajgelado

To isolate the issue, maybe you should try to do a simple loopback test first, a jumper between 8 and 10, and use minicom or picocom to get local echo.
 
BTW, in the case of Mainline, without having other uart enabled other than debug uart0, when I load overlay for uart2, it comes up as /dev/ttyS1, since debug is on /dev/ttyS0.