Repurpose Debug UART for 'normal' comms on Xavier NX

Autonomous Machines Jetson & Embedded Systems Jetson Xavier NX
6

hello pete28 ,

sorry, I realize that I should point-out this thread, Topic 160948.

the uart log on Xavier series is Tegra Combined UART, which means the uart log from CCPLEX and also BPMP can be seen in the default UART.

so,
please try below steps to disable TCU.

  1. modify mb1-bct.
  enable_combined_uart = 0;
  spe_uart_instance = 0xff;  // for UARTC: it was 0x2
  1. modify kernel device tree, to load uart8250 driver and update the bootargs.
  serial@c280000 {
       compatible = "nvidia,tegra20-uart"; // To load uart8250 driver
       status = "okay";
    };
  chosen {
       bootargs = "console=ttyS2,115200 earlycon=uart8250,mmio32,0x0c280000";
  };
  1. you may disassembler the bpmp-dtb, changes the content as following,
  -#include "parts/policy/serial-3-comb-uart.dtsi"
  +#include "parts/policy/serial-2-input.dtsi"

 / {
        serial {
-               port = <3>;
+               port = <2>;
                has_input;
-               combined-uart {
-                       enabled;
-               };
        };

 };
  1. update flash configure file, here’s an example to change from TCU0 to ttyS2 for UART-C.
  CMDLINE_ADD="console=ttyS2,115200n8 console=tty0 fbcon=map:0 net.ifnames=0 rootfstype=ext4";