[PATCH] Makefile: Fix include directory for OF_UPSTREAM

[Patrick Barsanti]

Hi Sumit,

On Wed, 29 May 2024 at 08:57, Sumit Garg <sumit.garg at linaro.org> wrote:

> Hi Patrick,
>
> On Tue, 28 May 2024 at 14:16, Patrick Barsanti
> <patrick.barsanti at amarulasolutions.com> wrote:
> >
> > Always prioritizing u-boot includes causes problems when trying to
> > migrate boards to OF_UPSTREAM that have divergent devicetree files with
> > respect to the upstream ones.
> >
> > For example, migrating a board based on `imx6ul.dtsi` to OF_UPSTREAM
> > breaks it, as there are some missing defines in the local dtsi file;
> > the solutions would be to either patch it, which defeats the purpose of
> > OF_UPSTREAM, or delete it entirely. This last option would then break all
> > the other boards which have not yet been migrated to OF_UPSTREAM.
>
> Can you elaborate more here regarding which dt-bindings headers
> conflict? Also, is it only the DTS files consumer for those headers or
> there are U-Boot drivers depending on them too?
>
> -Sumit
>

Sorry, I think I have worded my commit message wrong. I should
have used differ instead of diverge, which is slightly misleading.

The specific case I am talking about can be found in:
include/dt-bindings/clock/imx6ul-clock.h
dts/upstream/include/dt-bindings/clock/imx6ul-clock.h

The local header is missing the last commit from the kernel, which is
4e197ee880c2 ("clk: imx6ul: add ethernet refclock mux support").
This added some new defines, which are not present in the u-boot
header.
Following this commit, the `imx6ul.dtsi` was patched in the kernel to
use one of the new defines.

Because of this, at the current state, migrating a board which is
somehow based on `imx6ul.dtsi` will give a dtc error given by a value
being used in the upstream dtsi which is not defined in the local
header, because local includes always have priority with respect
to upstream ones even when setting OF_UPSTREAM.

Regards,
Patrick


> >
> > The opposite problem also exists: by always prioritizing upstream
> > includes, if changes are made in the kernel headers and devicetree
> > files that are not backwards compatible, again all boards which have not
> > been migrated to OF_UPSTREAM will break.
> >
> > This patch fixes this problem by prioritizing upstream includes when
> > `CONFIG_OF_UPSTREAM=y`, while keeping current prioritization when
> > it is not.
> >
> > Signed-off-by: Patrick Barsanti <patrick.barsanti at amarulasolutions.com>
> > ---
> >  Makefile | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> >
> > diff --git a/Makefile b/Makefile
> > index 79b28c2d81..899ae664ca 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -826,6 +826,19 @@ KBUILD_HOSTCFLAGS += $(if $(CONFIG_TOOLS_DEBUG),-g)
> >
> >  # Use UBOOTINCLUDE when you must reference the include/ directory.
> >  # Needed to be compatible with the O= option
> > +ifeq ($(CONFIG_OF_UPSTREAM),y)
> > +UBOOTINCLUDE    := \
> > +       -I$(srctree)/dts/upstream/include \
> > +       -Iinclude \
> > +       $(if $(KBUILD_SRC), -I$(srctree)/include) \
> > +       $(if $(CONFIG_$(SPL_)SYS_THUMB_BUILD), \
> > +               $(if $(CONFIG_HAS_THUMB2), \
> > +                       $(if $(CONFIG_CPU_V7M), \
> > +                               -I$(srctree)/arch/arm/thumb1/include), \
> > +                       -I$(srctree)/arch/arm/thumb1/include)) \
> > +       -I$(srctree)/arch/$(ARCH)/include \
> > +       -include $(srctree)/include/linux/kconfig.h
> > +else
> >  UBOOTINCLUDE    := \
> >         -Iinclude \
> >         $(if $(KBUILD_SRC), -I$(srctree)/include) \
> > @@ -837,6 +850,7 @@ UBOOTINCLUDE    := \
> >         -I$(srctree)/arch/$(ARCH)/include \
> >         -include $(srctree)/include/linux/kconfig.h \
> >         -I$(srctree)/dts/upstream/include
> > +endif
> >
> >  NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC)
> -print-file-name=include)
> >
> > --
> > 2.43.0
> >
>