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

[Graeme Russ]

Hi Simon

On Wed, Mar 21, 2012 at 11:19 AM, Simon Glass <sjg at chromium.org> wrote:
> Hi Graeme,
>
> On Tue, Mar 20, 2012 at 5:17 PM, Graeme Russ <graeme.russ at gmail.com> wrote:
>> Hi Simon,

>> And we are talking about one board vendor taking a SoC and using UARTA
>> for the panic output and another board vendor deciding to use UARTB - But
>> surely these vendors will create a separate config file for their boards.
>
> Nope. There is only one u-boot.bin for all boards that use this SOC.

And this is what I simply don't grok - Why have a single board config for
a range of boards that are obviously different?

I suppose I haven't dealt with device tree and I imagine that is what this
is all about. But to me, device trees are a construct for a higher level
of operation (the OS) not the boot loader (although I get that the boot
loader can parse the device tree in order to pick up what devices are
installed and need some kind of low-level initialisation)

I think at such a low level you really have to say 'hey, these boards are
different and need a different configuration' unless you put something in
hardware that allows U-Boot to pick up on the difference without needing
to initialise _anything_ similar to what Stephen has done to pass the
debug UART info to Linux via a scratch register

Regards,

Graeme