[PATCH] docs: dt: writing-schema: Extend expectations about example part of binding

[Krzysztof Kozlowski]

Document already used rules about example DTS in the binding:

 - All final device bindings (except sub-block of more complex devices)
   should have an example.

 - Phandles do not need to be resolvable - Sashiko already provided
   incorrect review, so this might help it to understand the concept.

 - Example should be complete, readable (use known defines), without
   'status' property.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxxxxx>
---
 .../devicetree/bindings/writing-schema.rst          | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/writing-schema.rst b/Documentation/devicetree/bindings/writing-schema.rst
index 3ffd0828617a..0f665b13c126 100644
--- a/Documentation/devicetree/bindings/writing-schema.rst
+++ b/Documentation/devicetree/bindings/writing-schema.rst
@@ -127,9 +127,16 @@ additionalProperties / unevaluatedProperties
         two above cases ('false').
 
 examples
-  Optional. A list of one or more DTS hunks implementing this binding only.
-  Example should not contain unrelated device nodes, e.g. consumer nodes in a
-  provider binding, other nodes referenced by phandle.
+  Optional, although expected in every device binding. A list of one or more
+  DTS hunks implementing this binding only.  Example should not contain
+  unrelated device nodes, e.g. consumer nodes in a provider binding, other
+  nodes referenced by phandles or node labels which are not directly referenced
+  in the example itself. Phandles in the example do not have to be resolvable.
+  The example must be complete as much as possible - have most of the
+  properties - and look readable to developers, thus for example use known
+  defines for interrupt or GPIO flags. Example should not contain 'status'
+  property in normal cases.
+
   Note: YAML doesn't allow leading tabs, so spaces must be used instead.
 
 Unless noted otherwise, all above schema properties are required.
-- 
2.53.0