Re: [PATCH net-next v2 1/2] dt-bindings: net: qcom,bam-dmux: Add memory-region and qcom,vmid properties

[Krzysztof Kozlowski]

On Sun, Sep 20, 2026 at 08:32:29AM +0530, Vishnu Santhosh wrote:
> Some Qualcomm SoCs, such as Shikra, run the modem in a separate security
> domain with restricted access to system memory. BAM-DMUX DMA mappings

Then this is specific to Shikra and should come with its compatible plus
constraints per variant.

> must therefore be constrained to a designated region that can be shared
> with the modem.
> 
> Add an optional memory-region property to reference a restricted DMA
> pool used for BAM-DMUX mappings, and a qcom,vmid property to identify the
> remote execution environment that is granted access to the pool through
> SCM.
> 
> Require memory-region whenever qcom,vmid is specified.
> 
> Co-developed-by: Deepak Kumar Singh <deepak.singh@xxxxxxxxxxxxxxxx>
> Signed-off-by: Deepak Kumar Singh <deepak.singh@xxxxxxxxxxxxxxxx>
> Signed-off-by: Vishnu Santhosh <vishnu.santhosh@xxxxxxxxxxxxxxxx>
> ---
>  .../devicetree/bindings/net/qcom,bam-dmux.yaml     | 38 ++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/qcom,bam-dmux.yaml b/Documentation/devicetree/bindings/net/qcom,bam-dmux.yaml
> index 33746c238513d72366bc52359fb10f275475b331..5351269b0ab72ede808ae47b55d57580af209038 100644
> --- a/Documentation/devicetree/bindings/net/qcom,bam-dmux.yaml
> +++ b/Documentation/devicetree/bindings/net/qcom,bam-dmux.yaml
> @@ -72,6 +72,24 @@ properties:
>        - const: tx
>        - const: rx
>  
> +  memory-region:
> +    maxItems: 1
> +    description:
> +      Phandle to a reserved-memory node compatible with restricted-dma-pool.
> +      The BAM-DMUX device uses the pool for DMA mappings.
> +
> +  qcom,vmid:
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    minItems: 1

Drop

> +    maxItems: 1
> +    items:
> +      minimum: 1
> +      maximum: 63
> +    description:
> +      VMID of the remote execution environment that is granted access to the
> +      restricted DMA pool through SCM. The local execution environment is
> +      retained automatically and must not be specified.
> +
>  required:
>    - compatible
>    - interrupts
> @@ -81,12 +99,29 @@ required:
>    - dmas
>    - dma-names
>  
> +dependencies:
> +  qcom,vmid: [ memory-region ]
> +
>  additionalProperties: false
>  
>  examples:
>    - |
> +    #include <dt-bindings/firmware/qcom,scm.h>
>      #include <dt-bindings/interrupt-controller/irq.h>
>  
> +    reserved-memory {
> +        #address-cells = <1>;
> +        #size-cells = <1>;
> +        ranges;
> +
> +        bam_dmux_pool: restricted-dma-pool {
> +            compatible = "restricted-dma-pool";
> +            size = <0x40000>;
> +            alignment = <0x40000>;
> +            alloc-ranges = <0x80000000 0x80000000>;
> +        };
> +    };

This wasn't here before. Drop.

Best regards,
Krzysztof