[PATCH 2/9] ARM: dts: socfpga: add Enclustra Intel AA1

[Sumit Garg]

On Sat, 5 Oct 2024 at 07:14, Marek Vasut <marex at denx.de> wrote:
>
> On 9/29/24 9:19 PM, Lothar Rubusch wrote:
> > On Sun, Sep 29, 2024 at 6:55 PM Marek Vasut <marex at denx.de> wrote:
> >>
> >> On 9/28/24 12:47 AM, Lothar Rubusch wrote:
> >>
> >> [...]
> >>
> >>>>> Ideally I like to setup some Kconfig choice for base board selection
> >>>>> and one for boot-mode.
> >>>>
> >>>>> 1.) In the documentation control.rst I read that the u-boot.dts is
> >>>>> combined of several elements. Is there a way to take this base .dts,
> >>>>> then add a base board .dtsi by Kconfig option, and similar a
> >>>>> boot-mode?
> >>>>
> >>>> The -u-boot.dtsi is preprocessed by C preprocessor, just like all the
> >>>> other DTs, so you can have a -u-boot.dtsi file which contains C
> >>>> preprocessor conditional statements in it to conditionally include other
> >>>> .dtsi files:
> >>>>
> >>>> #if IS_ENABLED(...)
> >>>> #include ...
> >>>> #else ...
> >>>> ...
> >>>> #endif
> >>>
> >>> Going through the include list setup by the Makefile made me find my
> >>> mistake. Currently I may use u-boot specific stuff in arch/arm/dts and
> >>> include generic .dtsi fragments from dts/upstream. Note: I'm not
> >>> setting CONFIG_OF_UPSTREAM since I'm using the regular include list
> >>> which already contains dts/upstream/src/arm/intel. Is this ok? Or,
> >>> shall I try a different approach, which involves having
> >>> CONFIG_OF_UPSTREAM explicitely set in the defconfig?
> >>
> >> I'm not quite sure I understand the question. Once this platform DTs
> >> land in mainline and the DTs get synchronized into U-Boot, you should
> >> then set CONFIG_OF_UPSTREAM. Until then, you could patch the DTs into
> >> dts/upstream/ to test the result with OF_UPSTREAM enabled .
> >>
> >
> > Ah, sorry. I did not explain well. Currently I patch the DTs which
> > should go to kernel/mainline into my local u-boot:
> > dts/upstream/src/arm/intel/socfpga/ as a preparation for my test
> > builds.
>
> OK
>
> > For U-boot I will need to build a devicetree file from archarm/dts. I
> > cannot rely just on the upstream fragments for u-boot. Imagine
> > settings like initial fpga bitstream loading, handoff file setup for
> > initialization, etc. In parts I may use .dtsi files from dts/upstream,
> > though, but most of the u-boot particular devicetree setup will reside
> > in arch/arm/dts, I guess (you may see later in the patches).
>
> You should be able to use dts/upstream/src/arm/intel/socfpga/ with
> -u-boot.dtsi from arch/arm/dts/ for this purpose, right ?

Yeah that's a possibility. But are there any plans on pushing
currently U-Boot specific DT bits to upstream DT (Linux kernel
source)?

>
> > I noticed when setting the option CONFIG_OF_UPSTREAM in `make
> > menuconfig`, it prepends `dts/upstream/` to the included paths of the
> > devicetree files. The resulting path for the .dts was then
> > dts/upstream/arch/arm/dts/ and could not be found anymore. When I
> > don't activate CONFIG_OF_UPSTREAM, dts/upstream is in the Makefile's
> > include list anyway so that I easily can include from both locations.
>
> +CC Sumit
>

Yeah that's true it's done on purpose to allow reuse of DT sources
includes (.dtsi or header files) even when CONFIG_OF_UPSTREAM isn't
enabled.

-Sumit

> > In conclusion, currently I'm calling a .dts for building the u-boot DT
> > from arch/arm/dts. The file includes upstream stuff as .dtsi fragment
> > from dts/upstream and handoff from local. CONFIG_OF_UPSTREAM does not
> > seem to be necessary in this case.
> >
> > This approach currently works for me. If you strongly disagree, I may
> > invest more time to find a way (or why there is currently no way) with
> > CONFIG_OF_UPSTREAM.
> >
> > This was my question about. Anyway you may wait on v3 to understand
> > better in source what I'm doing, or if I'm just messing around.
> I'll wait for V3, sure, good luck.
>
> Sorry for the delayed reply.