[U-Boot] [PATCH] ns16550: allow UART address to be set dynamically

[Wolfgang Denk]

Dear Graeme Russ,

In message <50CBD313.60508 at gmail.com> you wrote:
> 
> I can give you an example - Remote Telemetry Units (RTUs). They usually
> have a number of serial ports. The number of ports may vary based on the
> sub-model. Some ports may be RS-232, some may be RS-485 or RS-422.
> Depending on what additional devices you want to communicate with, you may
> need to use the 'console/diag' port to connect to a real device. So what
> you want to do is route console to another port (if available) or even
> netconsole.

Netconsole is always an option, and I think we also support switching
to other serial ports here and there (after relocation, that is).

But if you need console output before relocation (i. e. during
debugging), then I do not see why we cannot demand that the console
port is statically configured, and that you need corectly configured
images to have an early working console.

> I do get your point of view. But I think a combination of storing the
> dynamic console info in a DT format, the pre-console buffer and getting DT
> available as early as possible can yield a 'non-cludgy' solution. For board
> or SoC vendors who, for whatever reason, have implemented non-DT storage of
> hardware enumeration data they will be stuck with the penalty of having to
> translate that data into DT format before it can be parsed by U-Boot. Maybe
> this could be done in SPL. Yes, it's a hack, but if it can't be worked
> around, push it as low as possible and as far away from the U-Boot core as
> possible

I mostly agree here.  But I still fail to see why we havet os upport
this combination of early and dynamic - and only this is what causes
some issues.

Best regards,

Wolfgang Denk

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