Status of debug UART on am335x SoC

[Paul Barker]

Hi folks,

While looking into SPI boot failures on our am335x based boards I needed
to enable the debug UART to understand where u-boot was getting stuck.
I first enabled the following config options:

* CONFIG_DEBUG_UART=y
* CONFIG_DEBUG_UART_BASE=0x44e09000
* CONFIG_DEBUG_UART_CLOCK=48000000
* CONFIG_DEBUG_UART_OMAP=y
* CONFIG_DEBUG_UART_SHIFT=2
* CONFIG_DEBUG_UART_ANNOUNCE=y

With these options enabled the debug UART did not function, no output
was printed at all.

This was fixed by reverting commit 0dba45864b2a ("arm: Init the debug
UART"), as was discussed in another recent thread [1].

[1]: https://lore.kernel.org/all/CAJs94EYv55QBjvqB94Bwy-wv2_u7tJ+AMP0Ho_XAC8eqjT8BOQ@mail.gmail.com/

Has anyone had chance to look into this further?

It would be good to get this fixed so that the debug UART can be used on
these boards by simply enabling the correct config options. I'm happy to
help look into this if anyone has any pointers on where to start.

Thanks,

-- 
Paul Barker
Principal Software Engineer
SanCloud Ltd

e: paul.barker at sancloud.com
w: https://sancloud.com/
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