Set Other UART as Print Console

Follow the procedure below to complete the setting.

1. Find the target UART port in the board.dts file, and make sure the port has been enabled.

   &uart3 {
           pinctrl-names = "default"; 
           pinctrl-0 = <&uart3_pins>; 
           status = "okay";
   };

2. Modify the Kernel command line parameter which passed by the front boot step to use the target UART port as the printing console.

   earlyprintk console=ttyS3,115200 debug rootwait earlycon=sbi
   Note: 
   ttyS0 <=====> uart0 
   ttySl <=====> uartl 
   ttyS2 <=====> uart2 
   ttyS3 <=====> uart3