dt-bindings: kbuild: Split targets out to separate rules

Masahiro pointed out the use of if_changed_rule is incorrect and command
line changes are not correctly accounted for.

To fix this, split up the DT binding validation target,
dt_binding_check, into multiple rules for each step: yamllint, schema
validtion with meta-schema, and building the processed schema.

One change in behavior is the yamllint or schema validation will be
re-run again when there are warnings present.

Reported-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/all/20220817152027.16928-1-masahiroy@kernel.org/
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Documentation/devicetree/bindings/Makefile

@@ -37,24 +37,20 @@ CHK_DT_EXAMPLES := $(patsubst $(srctree)/%.yaml,%.example.dtb, $(shell $(find_cm
 quiet_cmd_yamllint = LINT    $(src)
       cmd_yamllint = ($(find_cmd) | \
                      xargs -n200 -P$$(nproc) \
-		     $(DT_SCHEMA_LINT) -f parsable -c $(srctree)/$(src)/.yamllint >&2) || true
+		     $(DT_SCHEMA_LINT) -f parsable -c $(srctree)/$(src)/.yamllint >&2) \
+		     && touch $@ || true
 
-quiet_cmd_chk_bindings = CHKDT   $@
+quiet_cmd_chk_bindings = CHKDT   $(src)
       cmd_chk_bindings = ($(find_cmd) | \
-                         xargs -n200 -P$$(nproc) $(DT_DOC_CHECKER) -u $(srctree)/$(src)) || true
+			  xargs -n200 -P$$(nproc) $(DT_DOC_CHECKER) -u $(srctree)/$(src)) \
+			  && touch $@ || true
 
 quiet_cmd_mk_schema = SCHEMA  $@
       cmd_mk_schema = f=$$(mktemp) ; \
                       $(find_all_cmd) > $$f ; \
                       $(DT_MK_SCHEMA) -j $(DT_MK_SCHEMA_FLAGS) @$$f > $@ ; \
 		      rm -f $$f
 
-define rule_chkdt
-	$(if $(DT_SCHEMA_LINT),$(call cmd,yamllint),)
-	$(call cmd,chk_bindings)
-	$(call cmd,mk_schema)
-endef
-
 DT_DOCS = $(patsubst $(srctree)/%,%,$(shell $(find_all_cmd)))
 
 override DTC_FLAGS := \
@@ -64,8 +60,15 @@ override DTC_FLAGS := \
 	-Wno-unique_unit_address \
 	-Wunique_unit_address_if_enabled
 
-$(obj)/processed-schema.json: $(DT_DOCS) $(src)/.yamllint check_dtschema_version FORCE
-	$(call if_changed_rule,chkdt)
+$(obj)/processed-schema.json: $(DT_DOCS) check_dtschema_version FORCE
+	$(call if_changed,mk_schema)
+
+always-$(CHECK_DT_BINDING) += .dt-binding.checked .yamllint.checked
+$(obj)/.yamllint.checked: $(DT_DOCS) $(src)/.yamllint FORCE
+	$(if $(DT_SCHEMA_LINT),$(call if_changed,yamllint),)
+
+$(obj)/.dt-binding.checked: $(DT_DOCS) FORCE
+	$(call if_changed,chk_bindings)
 
 always-y += processed-schema.json
 always-$(CHECK_DT_BINDING) += $(patsubst $(obj)/%,%, $(CHK_DT_EXAMPLES))