[PATCH v2 3/3] arm: mvebu: Initial ESPRESSOBin-Ultra board support

[Pali Rohár]

On Sunday 28 February 2021 22:38:26 Luka Kovacic wrote:
> Hello Marek,
> 
> On Sat, Feb 27, 2021 at 2:24 PM Marek Behun <marek.behun at nic.cz> wrote:
> >
> > In Linux the DTS for espressobin-ultra includes
> > armada-3720-espressobin.dtsi and just adds changes.
> >
> > If possible, please do this as is done in Linux. In fact we want to
> > slowly move in the direction to have the dts files just copied from
> > Linux.
> >
> > Marek
> 
> Thanks for pointing this out.
> As you and Pali have suggested, I will rework this patch to be as
> close to the Linux dts as possible.
> 
> I'd go with the approach of just creating a dts with changes with
> respect to the base ESPRESSOBin.
> 
> Kind regards,
> Luka

Hello Luka!

Linux kernel has currently 5 DTS files for espressobin (v5, v5-emmc, v7,
v7-emmc, ultra) and all are using one common dtsi file.

In U-Boot now we have just one DTS file for all 4 variants (ultra
variant is missing) and differences between emmc and non-emmc, v5 and v7
variants is done at u-boot runtime code.

So this allows to have just one U-Boot binary for all espressobin
boards.

Distributions (OpenWRT and Armbian) complained about need to have such
many precompiled binaries for espressobin. And seems that after unifying
u-boot to build just one espressobin binary, they are happy.

So, if it is possible, I would be happy if we can continue with this
approach with just one DTS file and one U-Boot binary for all
espressobin variants.

If it is needed to enable / disable some nodes in DTS file, it is
possible at U-Boot runtime via board_fix_fdt() function in board code.
Here can be e.g. code which checks if U-Boot is running at espressobin
v7 or at espressobin ultra. Maybe this could help you with debugging...