Re: [PATCH v10 4/5] dt-bindings: arm-smmu: add binding for Tegra194 SMMU

On Mon, Jul 13, 2020 at 8:10 AM Robin Murphy [off-list ref] wrote:

On 2020-07-10 21:29, Krishna Reddy wrote:

quoted

Thanks Rob. One question on setting "minItems: ". Please see below.

quoted

quoted

+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - nvidia,tegra194-smmu
+    then:
+      properties:
+        reg:
+          minItems: 2
+          maxItems: 2

quoted

This doesn't work. The main part of the schema already said there's only
1 reg region. This part is ANDed with that, not an override. You need to add an else clause with 'maxItems: 1' and change the base schema to
{minItems: 1, maxItems: 2}.

As the earlier version of base schema doesn't have "minItems: " set, should it be set to 0 for backward compatibility?  Or can it just be omitted setting in base schema as before?

We've always needed at least 1 "reg" specifier in practice, so I don't
think being backwards-compatible with broken DTs is a concern :)

'minItems: 0' would be a boolean (e.g. "reg;") and I'm not sure that's
even really valid json-schema. What you'd want here is 'reg' not
present (i.e. not in 'required').

Rob