Re: [PATCH v1 1/3] dt-bindings: sound: qcom,q6apm-dai: add optional qcom,vmid

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The device tree binding arbitrarily restricts `qcom,vmid` array elements to a maximum of 31, encoding an OS driver bug as a hardware constraint.
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commit adf539322d2d402e55788f41c212034d7e0a62e8
Author: Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>

dt-bindings: sound: qcom,q6apm-dai: add optional qcom,vmid

This commit adds an optional qcom,vmid property to the q6apm-dais node to
describe additional VMIDs that should be granted access to PCM DMA buffers.
It introduces a maximum value of 31 for the VMIDs to match the current SCM
source-permission mask handling.

> diff --git a/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml b/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml
> index 9e5b30d9c6e62..b767625985a74 100644
> --- a/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml
> +++ b/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml
> @@ -20,6 +20,16 @@ properties:
>      minItems: 1
>      maxItems: 2
>  
> +  qcom,vmid:
> +    description: Optional list of destination VMIDs to share PCM DMA buffers with.
> +      HLOS retains RW access as source owner and must not be listed.
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    items:
> +      minimum: 1
> +      maximum: 31

[Severity: Medium]
Does this artificially limit the hardware description based on a driver
implementation issue?

The commit message notes this matches current SCM source-permission mask
handling, but include/dt-bindings/firmware/qcom,scm.h defines valid VMIDs
that exceed 31 (e.g., QCOM_SCM_VMID_ADSP_HEAP = 37,
QCOM_SCM_VMID_CP_ADSP_SHARED = 51).

The limit of 31 seems to stem from the Linux qcom_scm_assign_mem() function
where it uses a 32-bit mask to track the source VMID mask. Should the device
tree binding allow higher VMIDs since bindings are meant to describe the
hardware capabilities rather than software limitations?

> +    minItems: 1
> +    maxItems: 8

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Sashiko AI review · https://sashiko.dev/#/patchset/20260609064038.492641-1-ajay.nandam@oss.qualcomm.com?part=1