Re: [PATCH v2 1/9] dt-bindings: dma: nvidia,tegra186-gpc-dma: Add iommu-map property

[Krzysztof Kozlowski]

On Mon, Mar 02, 2026 at 06:02:31PM +0530, Akhil R wrote:
> Add iommu-map property to specify separate stream IDs for each DMA
> channel. This enables each channel to be in its own IOMMU domain,
> keeping memory isolated from other devices sharing the same DMA
> controller.
> 
> Signed-off-by: Akhil R <akhilrajeev@xxxxxxxxxx>
> ---
>  .../devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml     | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml b/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml
> index 0dabe9bbb219..1e7b5ddd4658 100644
> --- a/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml
> +++ b/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml
> @@ -14,6 +14,7 @@ description: |
>  maintainers:
>    - Jon Hunter <jonathanh@xxxxxxxxxx>
>    - Rajesh Gumasta <rgumasta@xxxxxxxxxx>
> +  - Akhil R <akhilrajeev@xxxxxxxxxx>
>  
>  allOf:
>    - $ref: dma-controller.yaml#
> @@ -51,6 +52,10 @@ properties:
>    iommus:
>      maxItems: 1
>  
> +  iommu-map:
> +    minItems: 1
> +    maxItems: 32

Why is this flexible? If it is, means usually items are distinctive, so
I would expect defining/listing them. If they are not distinctive,
commit msg is incorrect. If the list is as simple as 1-to-1 channel
mapping, just add it in the description how they are ordered.

> +
>    dma-coherent: true
>  
>    dma-channel-mask:
> -- 
> 2.50.1
>