Re: [PATCH] arm: init: add an option to use FDT from previous bootloader

[Tom Rini <trini@konsulko.com>]

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On Tue, Oct 24, 2023 at 12:32:35PM +0100, Caleb Connolly wrote:

> Add a new config option to allow u-boot to reuse the FDT provided by the
> previous stage bootloader when available.
> 
> On some boards the previous stage bootloader can populate
> platform-specific parts of the devicetree such as the memory node, this
> allows us to avoid hardcoding it in u-boot and instead determine it
> dynamically at runtime.
> 
> Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
> ---
> This patch will improve generic support for Qualcomm boards by enabling
> us to configure the memory map at runtime rather than having hardcoded
> maps on a per-device basis. I've gone for this approach initially to try
> and avoid introducing board specific code where possible, but I'm happy
> to rework this into mach-snapdragon if that's preferred.
> ---
> base-commit: e65b5d35c9116485366bb08138043d51220551da
> 
> // Caleb (they/them)
> ---
>  arch/arm/lib/save_prev_bl_data.c |  7 +++++++
>  boot/Kconfig                     | 10 ++++++++++
>  include/init.h                   |  9 +++++++++
>  lib/fdtdec.c                     |  7 ++++++-

So what is different with this instead of using save_boot_params ? I'm
not saying this isn't needed, but I don't immediately see why
save_boot_params + (OF_HAS_PRIOR_STAGE=y&&OF_BOARD=y) isn't the solution
to the problem.

-- 
Tom

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