On Wed, Mar 25, 2020 at 04:05:41PM -0600, Rob Herring wrote:

Setting 'additionalProperties: false' is frequently omitted, but is
important in order to check that there aren't extra undocumented
properties in a binding.

Ideally, we'd just add this automatically and make this the default, but
there's some cases where it doesn't work. For example, if a common
schema is referenced, then properties in the common schema aren't part
of what's considered for 'additionalProperties'. Also, sometimes there
are bus specific properties such as 'spi-max-frequency' that go into
bus child nodes, but aren't defined in the child node's schema.

Acked-by: Mark Brown <broonie@kernel.org>