On Mon, Sep 23, 2019 at 06:15:08PM +0200, Ahmad Fatoum wrote:
> The layerscape features four UART ports termed UART{1-4} in the
> reference manual.
> In the upstream device tree they have the phandles &duart{0-3}.
>
> Currently, barebox follows the numbering used in the reference manual
> for the DEBUG_LL port, because that's what the <soc/fsl/immap_lsch2.h>
> header does as well.
>
> It's arguable however that the DEBUG_LL port should be 0-indexed,
> because users are most likely to look in the board device tree for the
> chosen stdout-path and that one's phandle is zero-indexed.
>
> One notable example of a target with one-indexed DEBUG_LL port is the
> i.MX, but there the uart port phandles are one-indexed, so there's no
> discrepancy between DEBUG_LL and /chosen/stdout-path like it's the
> case with the Layerscape.
>
> Fix the discrepancy by zero-indexing the layerscape UART.
>
> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
> ---
> I guess it can be argued that either way is the correct one.
Indeed ;)
> But I'd say from the viewpoint of a barebox developer, changing it to
> zero indexed makes the most sense.
If you could argue that it was inconsistent before and you make it
consistent now, then I would say go for it. Unfortunately it's
inconsistent now and still inconsistent with your patch, so changing
it IMO doesn't improve anything.
> help
> Select the UART port number used for early debugging here. Port
> - numbers start counting from 1.
> + numbers start counting from 0.
Actually I don't care much, so I may be convinced. What I do care about
though is that it's documented, and fortunately in this case it is ;)
Sascha
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