AM6442: Switch the console from MAIN UART0 to MCU UART0

Juraj Golej

Part Number: AM6442
Other Parts Discussed in Thread: TMDS64EVM

Tool/software:

Hello,

I have a custom board with the AM6442 MPU (but this question is also applicable to the TMDS64EVM devkit) and I want to switch the UART console from MAIN UART0 to MCU UART0 for all bootloaders and Linux. What modifications should I make in the BSP? My version of the BSP is ti-processor-sdk-linux-am64xx-evm-11.00.09.04.

I tried enabling the mcu_uart0 node in k3-am642-evm.dts and adding it to the "chosen" node, but it doesn't work.

chosen {
    stdout-path = &mcu_uart0;
};

&mcu_pmx0 {
	uartmcudbg_pins_default: uartmcudbg-default-pins {
		pinctrl-single,pins = <
			AM64X_MCU_IOPAD(0x0028, PIN_INPUT, 0) /* (A9) MCU_UART0_RXD.MCU_GPIO0_3 */
			AM64X_MCU_IOPAD(0x002c, PIN_OUTPUT, 0) /* (A8) MCU_UART0_TXD.MCU_GPIO0_2 */
		>;
	};
};

&mcu_uart0 {
	bootph-all;
	status = "okay";
	pinctrl-names = "default";
	pinctrl-0 = <&uartmcudbg_pins_default>;
};

4 months ago

+1 Bin Liu 4 months ago

TI__Guru**** 169071 points

Hi Juraj,

Please refer to the following link to change the console in U-Boot.

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1452385/am6442-change-boot-console-to-main_uart5-from-main_uart0

Please note that the devicetree file structure and location in U-Boot have been changed since SDK 11.0. Now the devicetree files are in two places in U-Boot:

1. <u-boot>/dts/upstream/src/arm64/ti/: the is the exact same copy of the devicetree files from kernel. To keep in sync with kernel, the files in this location should not be modified.

2. <u-boot>/arch/arm/dts/: the files here are U-Boot specific modification on top of the devicetree files in location #1. Any U-Boot devicetree customization should be done here.

0 Juraj Golej 4 months ago in reply to Bin Liu

Prodigy 100 points

Hi Bin,

this patch works great with main_uart3 but not with mcu_uart0/1. I had to add clock-frequency = <96000000>; to the DT node mcu_uartX and the console now works on the MCU UART as well.

Thanks.

0 Bin Liu 4 months ago in reply to Juraj Golej

TI__Guru**** 169071 points

Juraj,

Great catch!

Yes, this clock-frequency setting is needed in U-Boot since the mcu uart fclk by default is 96MHz, while the main uart default fclk is 48MHz which the uart driver assumes.

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AM6442: Switch the console from MAIN UART0 to MCU UART0