[U-Boot] [PATCH 21/24] tegra124: Implement spl_was_boot_source()

[Stephen Warren <swarren@wwwdotorg.org>]

On 05/04/2015 11:31 AM, Simon Glass wrote:
> Add an implementation of this function for Tegra.

> diff --git a/arch/arm/mach-tegra/board.c b/arch/arm/mach-tegra/board.c

> +#ifndef CONFIG_SPL_BUILD
> +void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3)
> +{
> +	from_spl = r0 != SPL_RUNNING_FROM_UBOOT;
> +	save_boot_params_ret();
> +}
> +#endif

(Using terminology from:
https://patchwork.ozlabs.org/patch/467771/
arm: spl: Enable detecting when U-Boot is started from SPL
)

That doesn't look right. Surely (at least on Tegra), if the r/o U-Boot 
chain-loads to the r/w U-Boot, then the chain-loaded U-Boot has no SPL 
and is just the main CPU build of U-Boot.

Hence, "SPL_RUNNING_FROM_UBOOT" seems incorrectly named, since the r/o 
U-Boot doesn't chain to SPL but rather to U-Boot.

This approach sounds a little brittle; what happens if r0 just happens 
to have that value. Won't the code get confused?

Why does U-Boot care whether it's been chain-loaded? Shouldn't it always 
behave identically in all cases, so it's independent of what caused it 
to run?