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

Krzysztof Kozlowski
2026-03-03T06:40:01Z

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@nvidia.com>
> ---
> .../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@nvidia.com>
> - Rajesh Gumasta <rgumasta@nvidia.com>
> + - Akhil R <akhilrajeev@nvidia.com>
>
> 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
>