Re: [PATCH v6 6/6] doc: board: mediatek: document Genio 510 and 700 SPL boot

[Carlo Caione <ccaione@baylibre.com>]

On Wed, Sep 09, 2026 at 14:56:02 +0100, David Lechner wrote:
> On 9/6/26 10:30 AM, Carlo Caione wrote:
> > Document the common Genio 510 and Genio 700 eMMC boot chain,
> > board-specific external firmware prerequisites, binman build invocation
> > and generated images.
> > 
> 
> ...
> 
> > +DDR-loader handoff contract
> > +---------------------------
> > +
> > +The DDR loader and U-Boot SPL have no parameter-block or firmware-call
> > +interface. Their contract consists of a fixed image layout, initialized DRAM
> > +and the execution state at the SPL entry point. Different DDR-loader
> > +implementations may be used as long as they satisfy this contract for the
> > +selected board. The BootROM loads the eMMC boot0 payload to
> > +``CONFIG_MTK_GENIO_BROM_LOAD_ADDR``::
> > +
> > +   offset 0                                     +----------------------+
> > +                                                | DDR loader           |
> > +                                                |                      |
> > +   offset CONFIG_MTK_GENIO_DDR_LOADER_SIZE      +----------------------+
> > +                                                | U-Boot SPL           |
> > +                                                | CONFIG_SPL_MAX_SIZE  |
> > +   image end                                    +----------------------+
> > +
> > +The DDR loader then performs the following handoff::
> > +
> > +   initialize and train DRAM
> > +
> > +   copy:
> > +     source      = CONFIG_MTK_GENIO_BROM_LOAD_ADDR
> > +                   + CONFIG_MTK_GENIO_DDR_LOADER_SIZE
> > +     destination = CONFIG_SPL_TEXT_BASE
> > +     size        = CONFIG_SPL_MAX_SIZE
> 
> Do CONFIG_MTK_GENIO_DDR_LOADER_SIZE and CONFIG_SPL_MAX_SIZE need to be the
> same or just CONFIG_SPL_MAX_SIZE >= CONFIG_MTK_GENIO_DDR_LOADER_SIZE?

They refer to two different things: CONFIG_MTK_GENIO_DDR_LOADER_SIZE
reserves space for the DDR loader while CONFIG_MTK_GENIO_DDR_LOADER_SIZE
is the size of the following SPL region which the loader copies to DRAM.

--
Carlo Caione