[U-Boot] [PATCH 07/14] dm: dts: omap: Select correct console for beaglebone

[Simon Glass]

Hi Tom,

On 22 October 2014 09:59, Tom Rini <trini at ti.com> wrote:
> On Mon, Sep 22, 2014 at 09:48:47AM -0600, Simon Glass wrote:
>
>> Select serial0 as the console.
>>
>> Signed-off-by: Simon Glass <sjg at chromium.org>
>> ---
>>
>>  arch/arm/dts/am335x-bone-common.dtsi | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/arm/dts/am335x-bone-common.dtsi b/arch/arm/dts/am335x-bone-common.dtsi
>> index 2f66ded..e70b4d1 100644
>> --- a/arch/arm/dts/am335x-bone-common.dtsi
>> +++ b/arch/arm/dts/am335x-bone-common.dtsi
>> @@ -10,6 +10,10 @@
>>       model = "TI AM335x BeagleBone";
>>       compatible = "ti,am335x-bone", "ti,am33xx";
>>
>> +     chosen {
>> +             stdout-path = &uart0;
>> +     };
>> +
>>       cpus {
>>               cpu at 0 {
>>                       cpu0-supply = <&dcdc2_reg>;
>
> So here's where I worry.  The reason we have a Kconfig for CONS_INDEX is
> that there are boards it's NOT uart0.  Setting aside the people with a
> "uart cape" (or otherwise breadboarding out another uart to a real
> connector), the industrial EVM is uart2 I want to say and we had been
> happily supporting this board with just a different build target (then
> defconfig).  What can we do here?  And yes, I see this is the bone DT
> not the EVM dt, but I'd rather not have to, if we don't have to at
> least, default to just not supporting the board (which is at least on
> the table, there's no DT for it in the kernel either).

I think we are looking for a build-time way to change the console. Is
that right? I suppose we could use a #define in the device tree, set
from some sort of include file / option, but that seems pretty ugly.

It would not be hard to modify the DT in the binary after it is built,
if that helps.

We can certainly support a different build target with a different
'default' device tree. We would then have several .dts files all
including the .dtsi for their main body.

Also there is a patch that I have not tidied/sent yet which builds all
the .dtb files for a class of boards, so you can add the .dtb that you
prefer to U-Boot with 'cat'.

I'm open to various options here, but I'm not sure which is best for
this use case.

I wonder how the kernel deals with this issue?

>
> As it stands however, it's right for what it's modifying so:
>
> Acked-by: Tom Rini <trini at ti.com>
>
> --
> Tom

Regards,
Simon