Alternate Debug Console without CON3

In retail version of OGA, there is no UART port from CON3.

If you want to solder 4pin connector on UART2 on OGA and OGS, please refer to this section.
4pin connector configuration of OGA and OGS

In case of OGA, An alternate debug console from 10pin header can replace it with kernel reconfiguration.
With this debug option, kernel debug is only available and u-boot option is not ready so far.

The alternate debug console is available for only OGA/OGA-BE.

To activate this function, you need to build kernel with one patch.

Currently, rockchip fiq debugger driver (via ttyFIQ0) is used as debug console function.
To switch output port flexibly, the following points can be adjusted for kernel.

Disable fiq-debugger

https://github.com/hardkernel/linux/blob/odroidgoA-4.4.y/arch/arm64/boot/dts/rockchip/rk3326-odroidgo2-linux.dts#L188 https://github.com/hardkernel/linux/blob/odroidgoA-4.4.y/arch/arm64/boot/dts/rockchip/rk3326-odroidgo2-linux-v11.dts#L199 https://github.com/hardkernel/linux/blob/odroidgoA-4.4.y/arch/arm64/boot/dts/rockchip/rk3326-odroidgo3-linux.dts#L236

	fiq-debugger {
		compatible = "rockchip,fiq-debugger";
		rockchip,serial-id = <2>;
		rockchip,wake-irq = <0>;
		/* If enable uart uses irq instead of fiq */
		rockchip,irq-mode-enable = <0>;
		rockchip,baudrate = <115200>;  /* Only 115200 and 1500000 */
		interrupts = <GIC_SPI 127 IRQ_TYPE_LEVEL_LOW>;
		pinctrl-names = "default";
		pinctrl-0 = <&uart2m1_xfer>;
                /* Change this point */
		status = "disabled";
	};

Enable UART2

Add the following in the dts file, too.

&uart2 {
	pinctrl-names = "default";
	pinctrl-0 = <&uart2m1_xfer>;
	status = "okay";
};

Through kernel command, it's available to assign console output.
Here is an example of boot.ini.

# console device setting
setenv condev "console=ttyS2,115200n8 console=tty0"   # on uart2 / display
# setenv condev "console=ttyS1,115200n8 console=tty0"   # on uart1 / display

# Boot Arguments
setenv bootargs "root=/dev/mmcblk0p2 rootwait rw fsck.repair=yes ${condev} net.ifnames=0 fbcon=rotate:3"