[U-Boot] SPL boot on iMX6

[Stefano Babic <sbabic@denx.de>]

Hi Tapani,

On 26/08/2013 09:17, Tapani Utriainen wrote:
> 
> Hello all,
> 
> we would like to have some comments how to architecture some patches we would 
> like to submit.

Nice

> 
> Background:
> 
> We have got SPL boot working, circumventing the need to have separate u-boot
> binaries depending on iMX6 CPU type and memory configuration. This allows us
> to have one (say) bootable SD card for all versions of our new SoMs.

Agree on this - we have already discussed in the past about this point,
and the way to get a single image for the different i.MX6 SOCs is to add
SPL support, moving part of the initialization stuff away from the DCD
table managed directly from the bootrom.

> 
> Formatting the patches presents us with some questions:
> 
> 1. Padconfigs. For some reason the existing padconfiguration macros are set
> compile time depending on target cpu variant. Hence the need to add new 
> macros (or smth) so the binary can configure the pads for many cpu variants.
> This would cause duplicate and redundant sets of pad configuration macros 
> for the imx6. Is there any alternative to this, more than rewriting code to 
> comply with cpu specific padconfigs?

Macros wee added exactly in the time they needed, and maybe a global
look was missing.

However, can you provide much more detail about this ? Which macros, in
which files ?

> 
> 2. Is there a minimum set of features that should be supported by new boards?
> (Thinking of features like fdt, fat or network boot).

No, there is not - the board maintainer is responsible to add the
features the board can. You can add support for a restricted number of
feature and later add a patch to full support the board.

> It seems that most imx6 based boards have some standard features enabled by
> default, but some of those we haven't tested on our new board.

You should dropped them, and add them again once they are tested and if
you really want to have them.

Best regards,
Stefano


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