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

[Stephen Warren]

On 12/13/2012 04:11 PM, Wolfgang Denk wrote:
> Dear Stephen Warren,
> 
> In message <50CA3E7A.8020407 at wwwdotorg.org> you wrote:
>>
>>>> My intent is that ODMDATA will definitely only be used for the console
>>>> UART, and will NOT be used for anything else like LCD, RTC, ... Those
>>>> other devices will certainly be configured via device tree.
>>>
>>> We've been there before, you know.
>>
>> I'm not quite sure what the implication is here.
> 
> What I mean is: there have been a number of times before when we
> decided to do something more or less ugly because it appeared to be
> the easiest / fastest / most simple approacht at that time,and we were
> sure we would it need for this one special case only.  Then it gor
> reused, and again, and it spread...
> 
>>> OK - what is the scope of visibility of such code?  Will it be
>>> strictly board specific only?  Or SoC specific? Arch? Global?
>>
>> It's partially SoC-specific, partially global.
> 
> Which exact parts would be global?

I guess by global you meant for any SoC/CPU/... U-Boot supports, whereas
I was treating global as across all Tegras.

So given that, the only global part would be the NS16550 patch I sent
out already. Anything else would be contained entirely within the Tegra
common board file.

> I am aware that the capability to set the UART is obviously part of
> the global code.

Right.

> But the actual implementation of such setting would be not global at
> all, right?

Right; it'd be part of that Tegra common board.c file, shared by all
Tegra boards, but should have zero impact outside any Tegra-specific code.

>> Note that by "all" and "global" here, I'm talking relative to all Tegra
>> SoCs, not about anything non-Tegra. "SoC-specific" means different for
>> Tegra20, Tegra30, Tegra114, etc.
> 
> OK.
> 
>> Note that in the latter case, I haven't pushed out the patches which
>> document the UART pinmux fields yet, but will very soon; most likely as
>> soon as we've resolved this conversation.
> 
> You guarantee that this all will remain strictly within Tegra specific
> areas, only?  And only for the UART?

Yes. I don't have any intention to use it for anything other than
console UART. I don't know of anyone else who wants to use it for
anything other than console UART. If anyone else tries to use it for
anything else, I'll give review comments not to, and direct them towards
device tree.

Of course, I can't predict the future, but that's just science, not my
trying to weasel out of a promise.