External dts building

[Giulio Benetti]

Hi Simon,

> Il giorno 14 ott 2021, alle ore 22:43, Simon Glass <sjg at chromium.org> ha scritto:
> 
> Hi Giulio,
> 
>> On Thu, 14 Oct 2021 at 13:23, Giulio Benetti
>> <giulio.benetti at benettiengineering.com> wrote:
>> 
>> Hi Simon,
>> 
>>>> Il giorno 14 ott 2021, alle ore 20:24, Simon Glass <sjg at chromium.org> ha scritto:
>>> 
>>> Hi,
>>> 
>>>> On Thu, 14 Oct 2021 at 07:46, Tom Rini <trini at konsulko.com> wrote:
>>>> 
>>>>> On Thu, Oct 14, 2021 at 02:53:30AM +0200, Giulio Benetti wrote:
>>>>> 
>>>>> Hello All,
>>>>> 
>>>>> is there a way to pass a dts file without touching the arch/arm/boot/dts/Makefile?
>>>>> 
>>>>> On Buildroot we support the possibility to pass an external dts by copying it to the uboot sources to
>>>>> be built but since uboot version 2020.01 it doesn’t work anymore.
>>>>> 
>>>>> So I’ve proposed a patch to prepend the dts file in the Makefile above, but this has drawbacks, like we reconfigure(it keeps adding files every time).
>>>>> 
>>>>> So I ask you, is there a more canonical way already to achieve this?
>>>> 
>>>> Not exactly, and it's something we're very much actively discussing
>>>> right now.
>>> 
>>> Are you using 'make DEVICE_TREE=xxx' ?
>> 
>> Yes but it doesn’t work if you don’t add an entry into arch/arm/dts/Makefile
>> Before version 2020.01 worked, but not after it.
> 
> What board are you building?

A20-OLinuXino-Lime_defconfig for but without CONFIG_DEFAULT_DEVICE_TREE undefined,
so if you try to pass DEVICE_TREE= pointing to an external .dts file copied to arch/arm/dts/ make doesn’t find the entry in Makefile and it can’t build it.

This is useful in build systems like Buildroot where you can provide an external defconfig as well as an external .dts file.

So here the solution I see is to create an entry in arch/arm/dts/Makefile on the top of the file afte copying the .dts file we want to build.
But on Buildroot they’ve pointed me to ask upstream(here) if there’s a more canonical way or to work together to achieve the goal:

https://patchwork.ozlabs.org/project/buildroot/patch/20210209201303.195093-1-giulio.benetti@benettiengineering.com/

Sorry if this e-mail is html but I’m on mobile :-/

Best regards
Giulio Benetti

> 
> Regards,
> Simon