[PATCH] docs: dt: writing-schema: Document usage of CHECK_DTBS make flag

["Nícolas F. R. A. Prado" <nfraprado@collabora.com>]

It is possible to run checks on a Devicetree by passing the CHECK_DTBS
flag when building. This is a useful shortcut to the dtbs_check make
target since it avoids checking unrelated Devicetrees, which can take
some time and is unnecessary if no bindings were modified. Document it.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>

---

 Documentation/devicetree/bindings/writing-schema.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/writing-schema.rst b/Documentation/devicetree/bindings/writing-schema.rst
index 4a381d20f2b4..55ad556472b4 100644
--- a/Documentation/devicetree/bindings/writing-schema.rst
+++ b/Documentation/devicetree/bindings/writing-schema.rst
@@ -167,6 +167,13 @@ setting the ``DT_SCHEMA_FILES`` variable to a specific schema file or pattern.
     make dt_binding_check DT_SCHEMA_FILES=/gpio/
     make dtbs_check DT_SCHEMA_FILES=trivial-devices.yaml
 
+Note that ``make dtbs_check`` will validate every DT source file that is
+enabled. When making changes to a DT but not to the bindings, a possible
+shortcut to validate only the DT in question is to explicitly build it with
+the ``CHECK_DTBS`` flag enabled. For example::
+
+    make CHECK_DTBS=y mediatek/mt8192-evb.dtb
+
 
 json-schema Resources
 ---------------------
-- 
2.38.1