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

[Marek Behun]

On Mon, 1 Mar 2021 16:41:01 +0100
Pali Rohár <pali at kernel.org> wrote:

> 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...

In that case try to make the "one dts file to rule them all" to be the
same as the basic dts file in Linux, and do the necessary U-Boot
differences in armada-3720-espressobin-u-boot.dtsi file. Then fix the
necessary differences for variants in board code.

Marek