[PATCH 1/1] dt-bindings: Fix error in 'make dtbs_check' when using DT_SCHEMA_FILES

[Cristian Ciocaltea <cristian.ciocaltea@gmail.com>]

If DT_SCHEMA_FILES is specified and contains more than one file paths,
'make dtbs_check' fails with the following message:

  $ make dtbs_check DT_SCHEMA_FILES="path/to/schema1.yaml path/to/schema2.yaml"
  SCHEMA  Documentation/devicetree/bindings/processed-schema.json
  Documentation/devicetree/bindings/Makefile:77: recipe for target 'Documentation/devicetree/bindings/processed-schema.json' failed
  make[1]: *** [Documentation/devicetree/bindings/processed-schema.json] Error 255
  make[1]: *** Deleting file 'Documentation/devicetree/bindings/processed-schema.json'
  Makefile:1364: recipe for target 'dt_binding_check' failed
  make: *** [dt_binding_check] Error 2

The error code 255 is returned by 'dt-mk-schema' when invoked as
'dt-mk-schema -j -u @<tmp-file>', where '<tmp-file>' is a temporary
file that is generated to contain a list of SPACE delimited schema
file paths, as indicated via DT_SCHEMA_FILES.

However, it seems the file format has been recently changed in
'dt-mk-schema', which now expects each schema path to be provided on
a separate line:

 $ dt-mk-schema --version
 2020.12.dev4+g6de1c45

Therefore, let's change '<tmp-file>' content format from

 path/to/schema1.yaml path/to/schema2.yaml ... path/to/schemaN.yaml

to

 path/to/schema1.yaml
 path/to/schema2.yaml
 ...
 path/to/schemaN.yaml

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
---
 Documentation/devicetree/bindings/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/Makefile b/Documentation/devicetree/bindings/Makefile
index f50420099a55..643eb873fd51 100644
--- a/Documentation/devicetree/bindings/Makefile
+++ b/Documentation/devicetree/bindings/Makefile
@@ -37,7 +37,7 @@ quiet_cmd_chk_bindings = CHKDT   $@
 quiet_cmd_mk_schema = SCHEMA  $@
       cmd_mk_schema = f=$$(mktemp) ; \
                       $(if $(DT_MK_SCHEMA_FLAGS), \
-                           echo $(real-prereqs), \
+                           printf '%s\n' $(real-prereqs), \
                            $(find_cmd)) > $$f ; \
                       $(DT_MK_SCHEMA) -j $(DT_MK_SCHEMA_FLAGS) @$$f > $@ ; \
 		      rm -f $$f
-- 
2.29.2