[PATCH 15/20] binman: Add support for alternative FDTs

[Simon Glass]

Hi Neha,

On Mon, 29 Jul 2024 at 22:44, Neha Malcom Francis <n-francis at ti.com> wrote:
>
> Hi Simon
>
> On 20/07/24 16:19, Simon Glass wrote:
> > FIT provides a way to select between different devicetree blobs
> > depending on the model. This works fine for U-Boot proper and allows SPL
> > to select the correct blob for the current board at runtime. The boot
> > sequence (SPL->U-Boot proper) is therefore covered by the existing
> > feature set.
> >
> > The first boot phase (typically TPL) cannot use FIT since SoC boot ROMs
> > don't currently support it. Therefore the TPL image must be specific to
> > each model it boots on.
> >
> > To support booting on mulitple models, binman must therefore produce a
> > separate TPL image for each model, even if the images for the rest of
> > the phases are identical.
> >
> > TPL needs to be packaged as an executable binary along with a reduced
> > devicetree. When multiple models are supported, a reduced devicetree
> > must be provided for each model.
> >
> > U-Boot's build system is designed to build a single devicetree for SPL
> > builds, so does not support this requirement.
> >
> > Add a new 'alternatives' feature to Binman, allowing it to automatically
> > subset a devicetree to produce the reduced devicetree for a particular
> > phase for each supported model. With this it is possible to produce a
> > separate TPL image for each of the models. The correct one can then be
> > loaded onto a board, along with the common FIT image(s).
> >
>
> Realized I caught up too late to this thread, and it's already pulled in,
> anyways thanks for the effort this was needed.

Thanks for looking through it...we'll see how it goes and what
adjustments are needed.

Regards,
Simon