Hi Rob,

On Tue, Dec 11, 2018 at 5:50 AM Rob Herring [off-list ref] wrote:

This adds the build infrastructure for checking DT binding schema
documents and validating dts files using the binding schema.

Check DT binding schema documents:
make dt_binding_check

Build dts files and check using DT binding schema:
make dtbs_check

Optionally, DT_SCHEMA_FILES can passed in with a schema file(s) to use

Perhaps, "can be passed" ?

In convention, the short log displays the target name
instead of the prerequisite.

If O=foo/bar is given, $< shows the full path,
then log will look like follows:


  CHKDT   /home/masahiro/ref/linux-devicetree/Documentation/devicetree/bindings/arm/calxeda.yaml
  DTC     Documentation/devicetree/bindings/arm/calxeda.example.dtb
  CHKDT   /home/masahiro/ref/linux-devicetree/Documentation/devicetree/bindings/arm/qcom.yaml
  DTC     Documentation/devicetree/bindings/arm/qcom.example.dtb
  CHKDT   /home/masahiro/ref/linux-devicetree/Documentation/devicetree/bindings/arm/xilinx.yaml
  DTC     Documentation/devicetree/bindings/arm/xilinx.example.dtb
  CHKDT   /home/masahiro/ref/linux-devicetree/Documentation/devicetree/bindings/arm/ti/nspire.yaml
  DTC     Documentation/devicetree/bindings/arm/ti/nspire.example.dtb
  CHKDT   /home/masahiro/ref/linux-devicetree/Documentation/devicetree/bindings/arm/ti/ti,davinci.yaml
  DTC     Documentation/devicetree/bindings/arm/ti/ti,davinci.example.dtb
  CHKDT   /home/masahiro/ref/linux-devicetree/Documentation/devicetree/bindings/arm/altera.yaml

You might think it is ugly.

+      cmd_chk_binding = (set -e; \
+                         $(DT_DOC_CHECKER) $< ; \
+                         mkdir -p $(dir $@) ; \
+                         $(DT_EXTRACT_EX) $< > $@ )

- 'set -e' is redundant because if_changed already has it.

- 'mkdir mkdir -p $(dir $@)' is also redundant because
   scripts/Makefile.build automatically creates it.

-  You do not need to execute this in a sub-shell



You can simplify like this:

       cmd_chk_binding = $(DT_DOC_CHECKER) $< ; \
                         $(DT_EXTRACT_EX) $< > $@

+$(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?

+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?

+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.

+$(obj)/$(DT_TMP_SCHEMA): $(addprefix $(srctree)/, $(DT_SCHEMA_FILES)) FORCE
+       $(call if_changed,mk_schema)

You do not need to prefix $(srctree)/ because Kbuild uses VPATH.


$(obj)/$(DT_TMP_SCHEMA): $(DT_SCHEMA_FILES) FORCE
       $(call if_changed,mk_schema)


is fine.

+cmd_dtc_yaml_chk = \
+       if ! echo "/dts-v1/; /{};" | $(DTC) -I dts -O yaml > /dev/null ; then \
+               echo "*"; \
+               echo "* dtc needs libyaml for DT schema validation support."; \
+               echo "* Install the necessary libyaml development package from your distro."; \
+               echo "*"; \
+               false; \
+       fi; \
+       touch $@
+
+$(objtree)/scripts/dtc/.dtc-yaml-chk.tmp: $(DTC) FORCE
+       $(call if_changed,dtc_yaml_chk)

Hmm, this is kind of ugly.

I'd rather check this in scripts/dtc/Makefile



How about something like below?

diff --git a/Makefile b/Makefile
index ff59adf..a3e2db2 100644
--- a/Makefile
+++ b/Makefile

@@ -1233,11 +1233,11 @@ ifneq ($(dtstree),)
        $(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@

 PHONY += dtbs dtbs_install dt_binding_check
-dtbs: prepare3 scripts_dtc
+dtbs dtbs_check: prepare3 scripts_dtc
        $(Q)$(MAKE) $(build)=$(dtstree)

-dtbs_check: prepare3 dt_binding_check
-       $(Q)$(MAKE) $(build)=$(dtstree) CHECK_DTBS=1
+dtbs_check: export CHECK_DTBS=1
+dtbs_check: dt_binding_check

 dtbs_install:
        $(Q)$(MAKE) $(dtbinst)=$(dtstree)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 8a7d622..5017175 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib

@@ -309,20 +309,7 @@ define rule_dtc_dt_yaml
        $(call echo-cmd,dtb_check) $(cmd_dtb_check)
 endef

-cmd_dtc_yaml_chk = \
-       if ! echo "/dts-v1/; /{};" | $(DTC) -I dts -O yaml > /dev/null ; then \
-               echo "*"; \
-               echo "* dtc needs libyaml for DT schema validation support."; \
-               echo "* Install the necessary libyaml development

package from your distro."; \
-               echo "*"; \
-               false; \
-       fi; \
-       touch $@
-
-$(objtree)/scripts/dtc/.dtc-yaml-chk.tmp: $(DTC) FORCE
-       $(call if_changed,dtc_yaml_chk)
-
-$(obj)/%.dt.yaml: $(src)/%.dts $(DTC) $(DT_TMP_SCHEMA) FORCE |
$(objtree)/scripts/dtc/.dtc-yaml-chk.tmp
+$(obj)/%.dt.yaml: $(src)/%.dts $(DTC) $(DT_TMP_SCHEMA) FORCE
        $(call if_changed_rule,dtc_dt_yaml)

 dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)

diff --git a/scripts/dtc/Makefile b/scripts/dtc/Makefile
index 056d5da..3e497f1 100644
--- a/scripts/dtc/Makefile
+++ b/scripts/dtc/Makefile

@@ -12,6 +12,10 @@ dtc-objs     += dtc-lexer.lex.o dtc-parser.tab.o
 HOST_EXTRACFLAGS := -I$(src)/libfdt

 ifeq ($(wildcard /usr/include/yaml.h),)
+ifeq ($(CHECK_DTBS),1)
+$(error dtc needs libyaml for DT schema validation support. \
+        Install the necessary libyaml development package.)
+endif
 HOST_EXTRACFLAGS += -DNO_YAML
 else
 dtc-objs       += yamltree.o

One drawback of this approach is,
this is not checked if you are using out-of-tree DTC.
Probably, Rob is the only person that overrides DTC.







-- 
Best Regards
Masahiro Yamada