[U-Boot] U-Boot image with multiple u-Boot dt blobs selected at low level boot

[Simon Glass]

Hi Oliver,

On 10 July 2017 at 07:54, Oliver Westermann <owestermann at gmail.com> wrote:
> Hello,
>
> I've got multiple ARM boards with similar but not quite the same
> configurations.
> For example different IO configurations for peripheral reset lines of
> hardware used in the u-boot phase.
>
> Currently I have multiple u-Boot configurations using multiple .dts files
> creating multiple u-boot.img and MLO files which are stored on the devices
> emmc (one set on every device).
> The u-boot than loads the linux kernel and the device specific linux dtb
> from a FAT partition on the device and boots (The linux partition has one
> kernel and multiple .dtb, so it supports all devices).
>
> The differences between the boards are GPIO related, but also power
> configuration & regulator settings.
>
> I would prefer to have a single u-boot.img and MLO file set to load onto
> all my devices. When I search the docs for this issue, I find many hints
> pointing me to u-boot FIT images, but from my point of view FIT issues
> multiple LINUX kernel and dt-blobs, not dt-blobs and configuration on the
> u-boot level.
>
> What would be the cleanest solution to load one uboot image, which has
> different behavior depending on the device it boots from?

If you don't mind handling this in SPL you can use spl_fit for this.
See board_fit_config_name_match() for where it matches the config.
Then it can load U-Boot with the correct device tree file. I have not
used it myself, but I believe this is what you want.

Regards,
Simon