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

[Rob Herring <robh@kernel.org>]

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? If so, then I think we can
remove the dependency.

Here's an example.

  SCHEMA  Documentation/devicetree/bindings/.schema.yaml.tmp
  CHKDT   Documentation/devicetree/bindings/arm/vt8500.yaml
  CHKDT   Documentation/devicetree/bindings/arm/zte.yaml
  CHKDT   Documentation/devicetree/bindings/arm/altera/socfpga-clk-manager.yaml
  CHKDT   Documentation/devicetree/bindings/arm/ti/ti,davinci.yaml
  CHKDT   Documentation/devicetree/bindings/arm/ti/nspire.yaml
  CHKDT   Documentation/devicetree/bindings/arm/spear.yaml
  CHKDT   Documentation/devicetree/bindings/arm/altera.yaml
warning: no schema found in file:
../Documentation/devicetree/bindings/arm/xilinx.yaml
/home/rob/proj/git/linux-2.6/Documentation/devicetree/bindings/arm/xilinx.yaml:
ignoring, error in schema 'onOf'
  CHKDT   Documentation/devicetree/bindings/arm/sti.yaml
  CHKDT   Documentation/devicetree/bindings/arm/qcom.yaml
  CHKDT   Documentation/devicetree/bindings/arm/primecell.yaml
  CHKDT   Documentation/devicetree/bindings/arm/cpus.yaml
  CHKDT   Documentation/devicetree/bindings/arm/sirf.yaml
  CHKDT   Documentation/devicetree/bindings/arm/calxeda.yaml
  CHKDT   Documentation/devicetree/bindings/arm/xilinx.yaml
  CHKDT   Documentation/devicetree/bindings/example-schema.yaml
/home/rob/proj/git/linux-2.6/Documentation/devicetree/bindings/arm/xilinx.yaml:
properties:compatible:onOf: 'onOf' is not one of ['$ref',
'additionalItems', 'allOf', 'const', 'contains', 'default',
'dependencies', 'description', 'enum', 'items', 'minItems', 'minimum',
'maxItems', 'maximum', 'not', 'oneOf', 'pattern', 'patternProperties',
'properties', 'required', 'type', 'typeSize']
make[2]: *** [../Documentation/devicetree/bindings/Makefile:12:
Documentation/devicetree/bindings/arm/xilinx.example.dts] Error 1

Rob