[PATCH] scripts/Makefile.lib: also consider $(CONFIG_SYS_BOARD)-u-boot.dtsi

[Rasmus Villemoes]

On 02/10/2023 20.56, Simon Glass wrote:
> Hi Tom,
> 
> On Mon, 2 Oct 2023 at 10:22, Tom Rini <trini at konsulko.com> wrote:
>>

>>> I'm really not sure that replacing build rules with a board CONFIG is
>>> a good idea. I suppose part of my confusion is why the Makefile is
>>> considered a problem?
>>
>> Because it's duplicative and as Rasmus points out, often wrong.
> 
> To me, that is under the control of the board maintainers. They should
> not put CONFIG_SYS_BOARD in the DT...it obviously goes against what DT
> is for and I'm not sure what binding would allow it anyway.
> 
> If it helps, I could do a little series to remove those? I think it is
> just arch/arm/dts/rockchip-optee.dtsi ?
> 
> This seems like a case of throwing the baby out with the bathwater.
> 

Huh? I don't think you understood what Tom was referring to, and I
certainly don't understand what you're talking about.

(1) duplicative = the _defconfig already has the necessary information
in *OF_LIST / DEFAULT_DEVICETREE

(2) often wrong = people add .dts targets to dtb-y, not .dtb targets.
They are harmless no-ops because people do get their .dtb files built
due to (1). "often" is perhaps a bit of an overstatement.

> We are trying to use DT (and not custom C code) to deal with the
> differences between boards. So long as that is preserved, I am happy
> enough.

Of course. This has nothing at all to do with C code versus device
tree(s). Just how we ensure that all relevant .dtbs that get built today
with the massive [mostly redundant] lists will still be built if we
remove all those dtb-$(FOO) += lists.

>>> The OF_LIST option is a little vague but I think it means that the DTs
>>> are packaged into a FIT in u-boot.img - is that right? But they
>>> presumably have to be built first.
>>
>> No, they don't have to be built first because scripts/Makefile.dts
>> ensures that we build everything in *OF_LIST.
> 
> That is from this commit:
> 
> 3609e1dc5f4 dts: automatically build necessary .dtb files
> 
> which was for use by custom boards using a private branch. Did it have
> a wider purpose that I didn't understand?

Not at the time, but it turns out that since we now _do_ have it, new
in-tree boards also don't have to modify an arch/*/dts/Makefile, and do
it wrong.

Rasmus