dtb: Filter out types with the wrong length multiple

If we have a property which can be a string or non-string type and its
value has empty strings in it, it gets incorrectly decoded a a non-string.
There's not a great way to solve this heuristic. Perhaps we could count
the number of non-zero length strings and pick string type if it is above
some percentage.

For now, when the length is not a multiple that fits the integer types, we
can for sure remove those integer types. If a string property happens to
have a length matching a integer multiple, then there's still a problem.

Signed-off-by: Rob Herring <robh@kernel.org>

dtschema/dtb.py

@@ -89,6 +89,13 @@ def prop_value(validator, nodename, p):
 
     # Filter out types impossible for the size of the property
     if len(prop_types) > 1:
+        if len(p) % 8:
+            prop_types -= {'int64', 'uint64', 'int64-array', 'uint64-array'}
+        if len(p) % 4:
+            prop_types -= {'int32', 'uint32', 'int32-array', 'uint32-array', 'phandle', 'phandle-array'}
+        if len(p) % 2:
+            prop_types -= {'int16', 'uint16', 'int16-array', 'uint16-array'}
+
         if len(p) > 4:
             prop_types -= {'int32', 'uint32', 'phandle'}
         else: