From c02bda09f91a340bc9fae4e236ce3e3ec6b1c9ff Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Fri, 29 Apr 2022 10:22:41 +0200 Subject: [PATCH] dt-bindings: arm-smmu: Document nvidia,memory-controller property 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. Note that this is a backwards-incompatible change that is, however, necessary to ensure correctness. Without the new property, most of the devices would still work but it is not guaranteed that all will. Reviewed-by: Rob Herring Acked-by: Will Deacon Signed-off-by: Thierry Reding Link: https://lore.kernel.org/r/20220429082243.496000-2-thierry.reding@gmail.com Signed-off-by: Will Deacon --- .../devicetree/bindings/iommu/arm,smmu.yaml | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml index 96891576a575e..ffd537a94a150 100644 --- a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml @@ -159,6 +159,17 @@ 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. + + If this property is absent, the mapping programmed by early firmware + will be used and it is not guaranteed that IOMMU translations will be + enabled for any given device. + $ref: /schemas/types.yaml#/definitions/phandle + required: - compatible - reg @@ -181,6 +192,12 @@ allOf: reg: minItems: 1 maxItems: 2 + + # The reference to the memory controller is required to ensure that the + # memory client to stream ID mapping can be done synchronously with the + # IOMMU attachment. + required: + - nvidia,memory-controller else: properties: reg: -- 2.30.2