Re: [PATCH 0/2] Add rpi5 specific defconfig

[Rasmus Villemoes <ravi@prevas.dk>]

On Fri, May 02 2025, Tom Rini <trini@konsulko.com> wrote:

> On Fri, May 02, 2025 at 01:34:33PM +0200, Bruno Leite wrote:
>
>> From: Bruno Leite <brule@prevas.dk>
>> 
>> 
>> Currently rpi5 uses a generic rpi_arm64_defconfig file that builds rpi4
>> devicetree. Add a defconfig that is specific to the rpi5 building the
>> now available upstream dts for that board. The defconfig makes use of
>> defconfig including that is now available and only changes the DTS
>> related config.
>> 
>> It is also necessary to add a more specific u-boot.dtsi to rpi5, since
>> due to the ARCH_BCM283X config it will try to build the
>> bcm283x-u-boot.dtsi and break.
>
> My question is, can we not adjust rpi_arm64_defconfig to be generic
> enough and not have a problem on Pi 5 due to the default device tree?

Not really.

What we want is to have CONFIG_DEFAULT_DEVICE_TREE to point at the
rpi5's .dts file, because we really want to build that and not some
"random" dts file that doesn't have anything to do with the hardware. I
know that kinda works for the setups where the .dtb built in U-Boot is
not used for anything, but in our case, we really do want to use the
.dtb from the U-Boot build - we inject various U-Boot specific stuff via
the EXTRA_DTSI mechanism, e.g. public key for kernel verification.

And due to CONFIG_SYS_SOC being bcm283x, and bcm283x-u-boot.dtsi
referencing nodes that simply don't exist when building
bcm2712-rpi-5-b.dts, the build breaks.

Perhaps the real problem is CONFIG_SYS_SOC being bcm283x for rpi5? I
don't really know why rpi4 is both bcm2711 and bcm2835 and what the
difference is, but rpi5 only seems to include a bcm2712.dtsi which does
not include further dtsi files.

If rpi5 has nothing to do with bcm283x, then perhaps a better approach
is to ensure that CONFIG_SYS_SOC is bcm2712 when building for
rpi5. Something like adding a CONFIG_TARGET_RPI_5 choice and adding a
'default "bcm2712" if TARGET_RPI_5' ?

Rasmus