Re: [PATCH 1/2] dt-bindings: sound: qcom,q6apm-dai: add memory-region property

[Krzysztof Kozlowski]

On Thu, Jun 18, 2026 at 05:05:08PM +0530, Ajay Kumar Nandam wrote:
> Document the new memory-region property that allows one or more
> reserved-memory carveout regions to be SCM-assigned to the VMIDs
> listed in qcom,vmid.
> 
> - Add memory-region as an optional phandle-array (1-8 entries).
>   Each entry must point to a shared-dma-pool, no-map reserved-memory
>   node. Index 0 is the control-path buffer; subsequent entries are
>   data-path buffers.
> - Enforce via dependentRequired that memory-region is only valid
>   when qcom,vmid is also present.
> - Expand qcom,vmid description to mention carveout regions and the
>   qcom_scm_is_available() probe-defer requirement.
> - Add a second example showing both properties in use with two
>   carveout regions and two destination VMIDs.
> 
> Signed-off-by: Ajay Kumar Nandam <ajay.nandam@xxxxxxxxxxxxxxxx>
> ---
>  .../bindings/sound/qcom,q6apm-dai.yaml        | 38 +++++++++++++++++--
>  1 file changed, 35 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml b/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml
> index b767625985a7..601055182da6 100644
> --- a/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml
> +++ b/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml
> @@ -10,7 +10,11 @@ maintainers:
>    - Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
>  
>  description: |
> -  This binding describes the Qualcomm APM DAIs in DSP
> +  This binding describes the Qualcomm APM DAIs in DSP.
> +  When qcom,vmid is present, the driver performs SCM memory
> +  assignment for PCM DMA buffers and any reserved-memory regions
> +  listed in memory-region, granting the specified VMIDs RW access
> +  while retaining HLOS as a co-owner.
>  
>  properties:
>    compatible:
> @@ -20,9 +24,24 @@ properties:
>      minItems: 1
>      maxItems: 2
>  
> +  memory-region:
> +    description:
> +      List of phandles to reserved-memory regions (shared-dma-pool,
> +      no-map) that must be SCM-assigned to the VMIDs in qcom,vmid.
> +      The first entry is the control-path buffer; subsequent entries
> +      are data-path buffers. Only meaningful when qcom,vmid is present.
> +    $ref: /schemas/types.yaml#/definitions/phandle-array

Drop ref, not needed.

> +    items:
> +      maxItems: 1
> +    minItems: 1
> +    maxItems: 8
> +
>    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.

This is confusing context. There is no qcom,vmid in this file.

Anyway, I think adding SCM interface and handling of VMIDs is quite
different design of this firmware/hardware, thus this should be a
different compatible.

Best regards,
Krzysztof