Linux image customisation - uart_1 to uart_3

hi, we are designing customized board with imx7. we have to use uart_3 for linux boot (as well as debug serial port). but by default linux image is coming with some other port (uart_1). where is the exact change in linux source code to change uart_1 to uart_3 ?. thanks.
elavarasan s

I assume you are talking about Colibri iMX7, correct?

The UART article has a list of UARTs and their Linux names. According to the table UART_3 (Colibri UART_C) is /dev/ttymxc2.

The debug serial console of Linux is not hardcoded, but a boot parameter set in U-Boot. By setting the environment variable console you can change the device you wish to be used:

setenv console ttymxc2

Linux user-space (systemd) will still start a a serial terminal on ttymxc0 by default. You can fix this by disabling the service:

systemctl disable serial-getty@ttymxc0.service

Or at OpenEmbedded build time by removing ttymxc0 from SERIAL_CONSOLE (in the machine file at meta-freescale-3rdparty/conf/machine/colibri-imx7.conf (or better yet change it to ttymxc2).

Changing the serial console of U-Boot gets a bit more involved. You need to alter the U-Boot UART pinmux in board/toradex/colibri_imx7/colibri_imx7.c as well as the U-Boot device tree arch/arm/dts/imx7-colibri.dts.

yes. sorry for the delay

thanks for the solution. i will check it. let me come again here if any more help required from you.