[U-Boot] SPL boot modes

[Joel A Fernandes]

On Fri, Sep 16, 2011 at 7:31 AM, Wolfgang Denk <wd at denx.de> wrote:
> Dear Joel A Fernandes,
>
> In message <CAD=GYpaAUVQo3S_8FOUfDLNAyUYS5cFs-fkL5GUv3oNnG_zerA at mail.gmail.com> you wrote:
>>
>> Just one question about one of your patches I happen to notice [1],
>> why is there a SPL build for each different boot mode such as for
>> NAND, MMC etc?. Wouldn't it be nicer to have a single SPL loader that
>> tried different boot modes one after the other, something like what
>> x-load already does? Are there are any challenges with this approach?
>
> Yes, this would be nice.  Question: how do we make this fit in - say -
> the 2 KiB code size that some processors load?  Including all the
> drivers for NAND, MMC etc.?

Hi Wolfgang,

Thanks for your email. I have to admit that I am new to the SPL way of
doing things but..

Based on which drivers have configured, we can cycle through the
available boot modes one after the other like:

#ifdef CONFIG_NAND
  nand_boot()
#endif
else
#ifdef CONFIG_MMC
  mmc_boot()
#endif
etc..

This should work for boards < 2k mem I'm guessing.

Also, we can allow the board to decide in which order to go through
based on preferences set in the board and/or config file.
For eg. (unless this is already done), it will nice if omap-like
boards can read through the sysboot pins to decide which order to try
the boot.

What do you think?

Thanks,
Joel