Re: [PATCH v2 01/10] spl: Decide about Falcon mode boot only once

Hi Alexey,

On 2026-07-31T17:10:44, Alexey Charkov <[email protected]> wrote:
> spl: Decide about Falcon mode boot only once
>
> Board implementations of spl_start_uboot() are not required to be
> idempotent - the documented examples sample a GPIO or read a character
> from the SPL console - so calling it more than once can yield different
> answers.
>
> Add spl_falcon_boot(), which calls spl_start_uboot() at most once and
> caches the result.
>
> Signed-off-by: Alexey Charkov <[email protected]>
>
> common/spl/spl.c | 18 ++++++++++++++++++
>  include/spl.h    | 11 +++++++++++
>  2 files changed, 29 insertions(+)

> diff --git a/common/spl/spl.c b/common/spl/spl.c
> @@ -105,6 +105,24 @@ __weak int spl_start_uboot(void)
> +bool spl_falcon_boot(void)
> +{
> +     static int falcon = -1;
> +
> +     if (falcon < 0)
> +             falcon = !spl_start_uboot();
> +
> +     return falcon;
> +}

Every existing loader (spl_mmc.c, spl_nand.c, etc.) still calls
spl_start_uboot() directly, so the mismatch you describe is still
possible on any of those paths when combined with spl_invoke_atf() - a
button released between the loader's call and spl_falcon_boot() in
spl_atf.c will produce exactly the disagreement this helper is meant
to prevent. Please convert the existing call sites as part of this
patch (or at least the ones on the ATF path), so the caching actually
delivers the guarantee.

> diff --git a/common/spl/spl.c b/common/spl/spl.c
> @@ -105,6 +105,24 @@ __weak int spl_start_uboot(void)
> +bool spl_falcon_boot(void)
> +{
> +     static int falcon = -1;

Minor - since the return type is bool, I'd find it cleaner to use two
bools (result and 'decided'), or an enum, rather than overloading an
int with a -1 sentinel. It also keeps the value out of .data, which
matters a little in SPL.

Regards,
Simon