Radxa CM3 support on Raspberry Pi Compute Module I/O board

[msgilligan]

It looks to me like the Radxa CM3 support in upstream/mainline U-Boot is only for the CM3 on the Radxa CM3 I/O board.

What do we need to do to add support for Radxa CM3 on Raspberry Pi CM4 I/O board?

@RadxaYuntian @RadxaNaoki

[msgilligan]

For reference, the Pine64 SoQuartz is a very similar compute module and U-boot has support for 3 different baseboards:

• Pine64 SOQuartz on Blade (soquartz-blade-rk3566)
• Pine64 SOQuartz on CM4-IO (soquartz-cm4-rk3566)
• Pine64 SOQuartz on Model A (soquartz-model-a-rk3566)

See https://docs.u-boot.org/en/latest/board/rockchip/rockchip.html#rockchip-boards

[RadxaYuntian]

@RadxaNaoki do you have plan to work on this?

[RadxaNaoki]

currently I don't have Raspberry Pi CM4 I/O board so it will not be available in near future.

[msgilligan]

I have one Radxa CM3 and I have the Raspberry Pi CM4 I/O Board and a DTV Electronics CMRat (which is supposed to be compatible with the RPi CM4 I/O Board) and am willing to do some testing.

Since most of the boards in nixos-rockchip are pulling mainline U-Boot, that is where I looked for CM3 + CM4IO support, but I suppose we could pull from another place if there is a version that has CM3 + CM4IO support.