OF_UPSTREAM vs. additional dtbs

[Sumit Garg]

Hi Jan,

On Thu, 5 Sept 2024 at 12:08, Jan Kiszka <jan.kiszka at siemens.com> wrote:
>
> On 04.09.24 19:29, Frank Wunderlich wrote:
> >
> >
> >> Gesendet: Mittwoch, 04. September 2024 um 19:16 Uhr
> >> Von: "Jan Kiszka" <jan.kiszka at siemens.com>
> >> OK, our overlay sources are on their way into mainline, will only take
> >> until 6.12-rc1 to get them here.

Glad to hear that.

> >> To accelerate the preparation, I ported
> >> that change to a local branch - just to find out that OF_UPSTREAM has no
> >> clue about DT overlays so far. And it is not just that there are no
> >> build rules for them (that was quickly fixed). It's also that there is
> >> no way to trigger their build for your u-boot proper.
> >>
> >> Are there plans for addressing this? I'm inclined to revive my patch
> >> that allows to augment dtb-y from the board's config.mk. Better suggestions?
> >
> > Hi
> >
> > i hang also on this part, in my case i build the dtbos for the vendor and try to use fdtoverlay to merge base-dt with the defined overlays.
> >
> > see commits till July 11th
> >
> > https://github.com/frank-w/u-boot/commits/2024-07-bpi-ofupstream-all/
> >
> > this fails because the target for fdtoverlays needs targets for the dtbos (have used the fdtoverlay target from linux)...
> > but i build then without dedicated target (while building the basedt).
> >
> > maybe you can help solving the "small" problem in makefile.
> >
>
> This is close but not quite the same scenario because I only need "our"
> dtbos, and there is no need to create dtbs with them applied (they will
> be used during dt fixup in our case).
>
> What I've now done is this:
>
> diff --git a/dts/Kconfig b/dts/Kconfig
> index 569d4be338e..7ea4fd5a79b 100644
> --- a/dts/Kconfig
> +++ b/dts/Kconfig
> @@ -226,11 +226,11 @@ config OF_LIST
>
>  config OF_OVERLAY_LIST
>         string "List of device tree overlays to include for DT control"
> -       depends on SPL_LOAD_FIT_APPLY_OVERLAY
>         help
>           This option specifies a list of device tree overlays to use for DT
>           control. This option can then be used by a FIT generator to include
> -         the overlays in the FIT image.
> +         the overlays in the FIT image or by binman when assembling an image
> +         that uses overlays during DT fixup.
>
>  choice
>         prompt "OF LIST compression"
> diff --git a/scripts/Makefile.dts b/scripts/Makefile.dts
> index 790f3c508f1..dc181240a21 100644
> --- a/scripts/Makefile.dts
> +++ b/scripts/Makefile.dts
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0+
>
>  dtb-y += $(patsubst %,%.dtb,$(subst ",,$(CONFIG_DEFAULT_DEVICE_TREE) $(CONFIG_OF_LIST) $(CONFIG_SPL_OF_LIST)))
> +dtb-y += $(patsubst %,%.dtbo,$(subst ",,$(CONFIG_OF_OVERLAY_LIST)))
>
>  ifeq ($(CONFIG_OF_UPSTREAM_BUILD_VENDOR),y)
>  ifeq ($(CONFIG_ARM64),y)
>

Yeah that's all you need to build DT overlays from dts/upstream
subtree. Care to send a proper patch for this?

>
> I will also provide a patch to enhance the machinery in dts/upstream
> /Makefile. This apparently plays no role when building U-Boot, but it
> would still be useful for validation purposes to have overlay support
> there.

As you mentioned we don't use Makefile for U-Boot builds. So it's
better to directly send that patch for inclusion in the DT rebasing
tree.

-Sumit

>
> Jan
>
> --
> Siemens AG, Technology
> Linux Expert Center
>