[PATCH 2/2] arm: mvebu: clearfog: Add defconfig for SPI booting

[Martin Rowe]

> > > I'm not sure how to run proper timing tests on the process, but
> > > stopwatch timing just between seeing "Trying to boot" and "U-Boot
> > > 2023.04-rc2" showed the return to BootROM under 1 second, and the
> > > direct from SPI around 4 seconds. I thought the goal of loading from
> > > SPI directly was speed, but returning to BootROM is significantly
> > > faster on this board.
> >
> > You should check SPI speed in DTS file and also in the defconfig.
>
> I think we have probably seen this slowdown before. There is a TODO in
> the way the DTS nodes are parsed by DM uclass. So this config must be
> set in defconfig to get around that bug:
> CONFIG_SF_DEFAULT_SPEED=50000000

That works and is much faster now. I'll submit it in a V2 for these
two patches once Pali's mvebu changes are accepted. Only question I
have is: should the faster speed be applied to all three defconfigs?
CONFIG_SF_DEFAULT_SPEED=1000000 (50x less) is implicitly added to the
MMC and SATA configs at the moment.