Linux/AM5726: Configuring debug UART in MLO

Kent Kanja

Intellectual 410 points

Part Number: AM5726

Tool/software: Linux

I'm trying to set the debug uart in MLO after changing the am57xx-idk-common.dtsi file to contain

chosen {

stdout-path = &uart2;

}

&uart2 {

status = "okay";

}

In serial_find_console_or_panic(), I end up with fdtdec_get_chosen_node(blob, "stdout-path") == -1

I do see the device tree code trying to match "serial@4806c000" but I have not yet figured out what else I am missing.

Please advise

over 7 years ago

0 Kemal R. Shakir over 7 years ago

TI__Guru 55345 points

Hello Kent,

May be you are missing the UART2 io delay pin multiplexing. Have you done that?

Best regards,
Kemal

0 Kent Kanja over 7 years ago in reply to Kemal R. Shakir

Intellectual 410 points

Kemal,

No, I have not done that. Can you point me to where this is done for uart3 (the default)? I should be able to base my change on that.

Thanks!

0 Kent Kanja over 7 years ago in reply to Kent Kanja

Intellectual 410 points

One more detail that I hope will help determine what I'm missing:

I put a breakpoint in fdt_subnode_offset_namelen(...) and for names containing "serial@", I only see "serial@4806a000" (UART1) "and serial4802000" (UART3) show up as arguments to memcmp(...)

0 Kemal R. Shakir over 7 years ago in reply to Kent Kanja

TI__Guru 55345 points

To change the debug UART in MLO, you need to change the &uartX in <Processor SKD>/board-support/u-boot-<version>/arch/arm/dts/omap5-u-boot.dtsi.

0 Kent Kanja over 7 years ago in reply to Kemal R. Shakir

Intellectual 410 points

adding the property "u-boot,dm-pre-reloc" to the desired uartX nodes in my .dts or .dsti files seems to work as well. It wasn't clear that omap5-u-boot.dtsi was being implicitly included.

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Linux/AM5726: Configuring debug UART in MLO