Re: [PATCH 1/4] dt-bindings: arm-smmu: Document nvidia,memory-controller property

[Rob Herring <robh@kernel.org>]

On Fri, Nov 12, 2021 at 02:12:28PM +0100, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> On NVIDIA SoC's the ARM SMMU needs to interact with the memory
> controller in order to map memory clients to the corresponding stream
> IDs. Document how the nvidia,memory-controller property can be used to
> achieve this.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  Documentation/devicetree/bindings/iommu/arm,smmu.yaml | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> index f66a3effba73..cf32a7955475 100644
> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> @@ -155,6 +155,12 @@ properties:
>    power-domains:
>      maxItems: 1
>  
> +  nvidia,memory-controller:
> +    description: A phandle to the memory controller on NVIDIA Tegra186
> +      and later SoCs. The memory controller needs to be programmed with
> +      a mapping of memory client IDs to ARM SMMU stream IDs.
> +    $ref: /schemas/types.yaml#/definitions/phandle
> +
>  required:
>    - compatible
>    - reg
> @@ -177,6 +183,9 @@ allOf:
>          reg:
>            minItems: 1
>            maxItems: 2
> +
> +      required:
> +        - nvidia,memory-controller

That's not a compatible change. Document why it is necessary if that's 
intended.

>      else:
>        properties:
>          reg:
> -- 
> 2.33.1
> 
>