Design proposal for dual BMC flash with "golden image"

[Lei Yu]

On Wed, Sep 16, 2020 at 5:55 PM Ivan Mikhaylov <i.mikhaylov at yadro.com> wrote:
> > For now, we use "devmem" to manipulate the registers for testing purpose.
> > It's nice to have that driver, but in productions there will be no
> > need to use devmem nor the ioctl on watchdog, so it's not a must for
> > us to use the driver.
> >
>
> And how you switch safely into golden side in this case?
>

The plan is:
1. When the primary flash is broken and u-boot could not be started,
aspeed will switch to the golden side automatically.
2. When the primary flash's u-boot is OK, but the kernel/rofs fails a
couple of times, the u-boot could detect this and switch to the golden
side by setting the related registers. See example in
https://github.com/openbmc/openbmc/blob/master/meta-phosphor/aspeed-layer/recipes-bsp/u-boot/files/0005-config-ast-common-Fall-back-to-secondary-flash-on-fa.patch