u-boot DT configuration node

[Mark Kettenis]

> From: Michal Simek <michal.simek at xilinx.com>
> Date: Wed, 1 Apr 2020 11:23:13 +0200
> 
> Hi Rob and others,
> 
> for couple of years already u-boot is using config node in root DT for
> u-boot configuration.
> 
> Here is one example in u-boot source code.
> https://gitlab.denx.de/u-boot/u-boot/-/blob/master/arch/arm/dts/exynos5250-spring.dts#L47
> 
> And here is dt binding description
> https://gitlab.denx.de/u-boot/u-boot/-/blob/master/doc/device-tree-bindings/config.txt
> 
> I was checking dt binding specification and there no such a thing
> described there. It means I expect this is more adhoc u-boot solution.
> We have reached the point where could be beneficial to put some u-boot
> specific configurations to DT.
> 
> Actually I have done similar thing some time ago too by using chosen
> node and add xilinx specific property there to point to eeprom.
> https://gitlab.denx.de/u-boot/u-boot/-/blob/master/arch/arm/dts/zynqmp-zcu102-revA.dts#L39
> 
> I think it is a time to discuss it and do it properly.
> 
> First of all my question is where we could list SW prefixes to make sure
> that they are listed and everybody is aware about it. We have
> vendor-prefixes and we should have a way to record also prefixes for sw
> projects. U-Boot is using u-boot. Xen has file in the kernel with using
> xen prefix. At least these two should be listed.

OpenBSD is using "openbsd," as a prefix.  I've always thought it would
be good to have it listed in the list of vendor prefixes there.  In an
open source world it shouldn't matter whether an entity sells
something or not.  And in fact "inux," is already there.  And so is
"qemu,".

> Next my question is what is the recommended way to pass sw specific
> parameters via DT? I think using chosen node is more appropriate then
> adhoc config node. Or is there a better way how this should be done?

On OpenBSD we do indeed use the the chosen node to pass information
between the bootloader and the kernel.

Cheers,

Mark