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

[Stephen Warren]

On 12/17/2012 03:37 PM, Wolfgang Denk wrote:
> Dear Stephen Warren,
> 
> In message <50CF9BAA.3050504 at wwwdotorg.org> you wrote:
>>
>> There are many ways besides device tree to enumerate hardware. For
>> example, consider PCI or USB (albeit USB isn't memory mapped). I don't
> 
> Yes, there are.  But your console port cannot be compred against
> dynamically populated and scannable bus interfaces like USB or PCI,
> and I think you are aware of that.

I honestly don't know why you couldn't have a PCI-based console UART.

>> think we should tie any new U-Boot dynamic device registration API to
>> device tree, since that would seem to prevent (or imply against) usage
>> of that API with PCI for example.
> 
> Not any dynamic device registration.  But here, it actually AIN'T
> dynamic - it is fully static, just board dependent.

If you want to run the same U-Boot binary on multiple different boards,
then that does make the UART selection dynamic. There's no conceptual
difference between dynamic information coming from a DT passed to U-Boot
at runtime, SoC-defined enumeration/selection mechanisms such as Tegra's
ODMDATA, or scanning a PCI bus.

Or, is U-Boot going to ban addressing TI's case where the UART selection
is stored in an I2C EEPROM that can be read at run-time, since instead
during flashing that information could be extracted and hard-coded into
the board's device tree instead?