Re: [PATCH 03/17] dt-bindings: display/msm: Document Nord MDSS

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The 'qcom,nord-dp' compatible string is omitted from generational 'if-then' constraint blocks.
- [Medium] The compatible string 'qcom,nord-dpu' is referenced for the child display controller, but the corresponding DPU binding update is entirely missing from the patch series.
--

commit 64dd6c393c789d34e5fe84cef41d36aca32b8df0
Author: Mahadevan P <mahadevan.p@oss.qualcomm.com>

dt-bindings: display/msm: Document Nord MDSS

Add the binding for the display subsystem (MDSS) found on the Qualcomm
Nord SoC. Nord is MDSS 12.1, DP-only (no DSI), with two independent DP
controllers.

> diff --git a/Documentation/devicetree/bindings/display/msm/qcom,nord-mdss.yaml b/Documentation/devicetree/bindings/display/msm/qcom,nord-mdss.yaml
> new file mode 100644
> index 0000000000000..0b0cacdca9dbd
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/msm/qcom,nord-mdss.yaml
> @@ -0,0 +1,98 @@
[ ... ]
> +patternProperties:
> +  "^display-controller@[0-9a-f]+$":
> +    type: object
> +    additionalProperties: true
> +    properties:
> +      compatible:
> +        const: qcom,nord-dpu

[Severity: Medium]
Is the schema binding for qcom,nord-dpu entirely missing from this patch
series?

This compatible string is referenced here for the child display controller,
but the corresponding DPU binding update is omitted.

Without it, full schema validation for the DPU child node cannot occur when
validating a device tree containing qcom,nord-dpu.

> +
> +  "^displayport-controller@[0-9a-f]+$":
> +    type: object
> +    additionalProperties: true
> +    properties:
> +      compatible:
> +        const: qcom,nord-dp

[Severity: Medium]
This isn't a bug introduced by this patch, but by an earlier patch in this
series that added qcom,nord-dp to the top-level compatible enum without
updating the constraint blocks.

Should qcom,nord-dp be included in the generational if-then constraint blocks
in dp-controller.yaml to enforce precise hardware constraints?

Looking at Documentation/devicetree/bindings/display/msm/dp-controller.yaml,
at the start of the generational conditional blocks:

    allOf:
      # AUX BUS does not exist on DP controllers

By omitting the string from these constraint blocks, device trees for
qcom,nord-dp with invalid configurations (e.g., an incorrect number of clocks
or register regions) will silently pass schema validation when running
dt_binding_check or dtbs_check against a Nord DP node.

They will fall back to the overly permissive top-level defaults (up to 9 reg
items and 8 clocks).

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260911-nord-drv-dt-v1-0-e25c073cf1b6@oss.qualcomm.com?part=3