Extracting empty examples results in just the empty template being
generated and then validated. That's pointless and not free, so filter
out the schemas without any examples from the targets.

There's currently a little less than 10% of the binding schema files
without examples. Removing them improves the build time by ~6%.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
---
 Documentation/devicetree/bindings/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/Makefile b/Documentation/devicetree/bindings/Makefile
index 8390d6c00030..8d6f85f4455d 100644
--- a/Documentation/devicetree/bindings/Makefile
+++ b/Documentation/devicetree/bindings/Makefile
@@ -32,7 +32,8 @@ find_cmd = $(find_all_cmd) | \
 		sed 's|^$(srctree)/||' | \
 		grep -F -e "$(subst :," -e ",$(DT_SCHEMA_FILES))" | \
 		sed 's|^|$(srctree)/|'
-CHK_DT_EXAMPLES := $(patsubst $(srctree)/%.yaml,%.example.dtb, $(shell $(find_cmd)))
+CHK_DT_EXAMPLES := $(patsubst $(srctree)/%.yaml,%.example.dtb, \
+			      $(shell $(find_cmd) | xargs grep -l '^examples:'))
 
 quiet_cmd_yamllint = LINT    $(src)
       cmd_yamllint = ($(find_cmd) | \
-- 
2.51.0