[U-Boot] [PATCH] tegra: Specify debugging serial port at boot.

[Simon Glass]

Hi Stephen,

On Tue, Mar 20, 2012 at 5:42 PM, Stephen Warren <swarren at wwwdotorg.org> wrote:
> On 03/20/2012 05:33 PM, Simon Glass wrote:
> ...
>> We cannot select the UART via CONFIG - remember that all of these
>> boards have the same U-Boot binary. Please read that again :-) The
>> device tree is the only thing that distinguishes them. All of the
>> CONFIG options are identical for all boards.
>
> I don't agree that all the boards have the same U-Boot binary. At
> present, there are about 6 Tegra boards in mainline U-Boot all with
> different binaries.

Er, I was referring to all the boards that use the same config, not
all the boards in mainline U-Boot. However I agree that we currently
have 6 boards, we could fairly easily change this into one board with
a device tree selector.

>
> Even with DT, I don't see anything wrong with having the low-level init
> code parameterized and built per board (e.g. debug UART), but all the
> higher level devices initialized/configured from device tree (e.g. I2C,
> MMC, USB).

It doesn't achieve the design goal I mentioned, but yes this is possible.

>
> Even if the binary result from the boot process is identical, but we did
> something like I proposed a few emails back to inject the correct UART
> ID into an initially common binary, you still get left with different
> binaries per board, in terms of what you're actually flashing onto the
> board.
>
> (yes, I'd be interested in seeing the SPL code you mentioned)

OK. Let me know if we are on the same page on this topic, and I will
start a new thread...

Regards,
Simon