Re: [PATCH v3] kbuild: Add support for DT binding schema checks

[Masahiro Yamada <yamada.masahiro@socionext.com>]

On Wed, Dec 12, 2018 at 3:36 AM Rob Herring <robh@kernel.org> wrote:
>
> On Tue, Dec 11, 2018 at 10:03 AM Masahiro Yamada
> <yamada.masahiro@socionext.com> wrote:
> >
> > On Wed, Dec 12, 2018 at 12:13 AM Rob Herring <robh@kernel.org> wrote:
> >
> > >
> > > > > +$(obj)/%.example.dts: $(src)/%.yaml FORCE
> > > > > +       $(call if_changed,chk_binding)
> > > > > +
> > > > > +DT_TMP_SCHEMA := .schema.yaml.tmp
> > > >
> > > >
> > > > BTW, why does this file start with a period?
> > > > What is the meaning of '.tmp' extension?
> > >
> > > Nothing really. Just named it something so it gets cleaned and ignored by git.
> >
> >
> > It is cleaned whatever file name you use.
> >
> >
> > See scripts/Makefile.clean
> >
> > __clean-files   := $(extra-y) $(extra-m) $(extra-)       \
> >                    $(always) $(targets) $(clean-files)   \
> >                    $(hostprogs-y) $(hostprogs-m) $(hostprogs-) \
> >                    $(hostlibs-y) $(hostlibs-m) $(hostlibs-) \
> >                    $(hostcxxlibs-y) $(hostcxxlibs-m)
> >
> >
> > $(extra-y) is cleaned.
>
> True.
>
> >
> >
> > You are adding *.example.dts to .gitignore
> >
> > Why not "schema.yaml" ?
>
> Okay. I'll do "processed-schema.yaml" to give a bit better name of
> what it contains.
>
> >
> > > > > +extra-y += $(DT_TMP_SCHEMA)
> > > > > +
> > > > > +quiet_cmd_mk_schema = SCHEMA  $@
> > > > > +      cmd_mk_schema = mkdir -p $(obj); \
> > > > > +                      rm -f $@; \
> > > > > +                      $(DT_MK_SCHEMA) $(DT_MK_SCHEMA_FLAGS) -o $@ $(filter-out FORCE, $^)
> > > >
> > > >
> > > > "mkdir -p $(obj)" is redundant.
> > > >
> > > >
> > > > Why is 'rm -f $@' necessary ?
> > > > Can't dt-mk-schema overwrite the output file?
> > >
> > > It is for error case when the output file is not generated. I can
> > > handle this within dt-mk-schema instead.
> > > > > +DT_DOCS = $(shell cd $(srctree)/$(src) && find * -name '*.yaml')
> > > > > +DT_SCHEMA_FILES ?= $(addprefix $(src)/,$(DT_DOCS))
> > > > > +
> > > > > +extra-y += $(patsubst $(src)/%.yaml,%.example.dts, $(DT_SCHEMA_FILES))
> > > > > +extra-y += $(patsubst $(src)/%.yaml,%.example.dtb, $(DT_SCHEMA_FILES))
> > > >
> > > >
> > > >
> > > > I assume you intentionally did not do like this:
> > > >
> > > > extra-y += $(patsubst %.yaml,%.example.dtb, $(DT_DOCS))
> > > >
> > > > From the commit description, DT_SCHEMA_FILES might be overridden by a user.
> > > > So, I think this is OK.
> > > >
> > > >
> > > >
> > > >
> > > > > +$(obj)/$(DT_TMP_SCHEMA): | $(addprefix $(obj)/,$(patsubst $(src)/%.yaml,%.example.dtb, $(DT_SCHEMA_FILES)))
> > > >
> > > > I do not understand this line.
> > > > Why is it necessary?
> > > >
> > > > *.example.dtb files are generated anyway
> > > > since they are listed in extra-y.
> > >
> > > It is enforcing the ordering. Without it, the binding checks and
> > > building .schema.yaml.tmp happen in parallel because both only have
> > > the source files as dependencies. The '|' keeps the dependencies out
> > > of the dependency list($^).
> >
> >
> > What kind problem would you see if
> > the binding checks and building .schema.yaml.tmp
> > happen in parallel?
>
> In case of no errors in the binding docs, it doesn't matter. If there
> are errors, I don't want the dtbs validation to run if any schema
> doesn't validate. However, I played around with this a bit more and it
> seems like having the examples' dts/dtb in extra-y prevents that from
> happening. Does that match your expections?

Exactly.

If any error occurs in Documentation/devicetree/bindings/Makefile,
Make terminates before proceeding to the dtbs_check stage.



-- 
Best Regards
Masahiro Yamada

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