Re: [PATCH v2 02/12] dt-bindings: media: qcom,sm8550-iris: Add context bank subnodes

On Fri, Jul 31, 2026 at 11:52:17PM +0530, Vikash Garodia wrote:
> The VPU issues DMA through several SMMU streams, and the hardware does
> not give every stream the same addressable range. The non-pixel stream
> is restricted to use 0-600MB of IOVA space, while the pixel stream can
> address the full range:
>     +-----------------------------------------------------------+
>     | non-pixel stream addressable range (600 MB - 3.5 GB)      |
>     | 0x25800000 - 0xe0000000                                   |
>     +-----------------------------------------------------------+
>     | pixel stream addressable range (0 - 3.5 GB)               |
>     | 0x00000000 - 0xe0000000                                   |
>     +-----------------------------------------------------------+
> A single "iommus" property on the video-codec node puts every stream in
> one IOMMU domain sharing one IOVA allocator, so nothing keeps a
> non-pixel buffer above 600 MB. Once an allocation lands below that
> boundary the hardware faults, which shows up as unhandled SMMU page
> faults and spontaneous reboots:
> https://gitlab.freedesktop.org/drm/msm/-/work_items/100
> 
> Reference qcom,venus-common.yaml, which describes the per-stream context
> bank subnodes, and drop "iommus" from the required list. The common
> schema accepts either the flat "iommus" or the "non-pixel" and "pixel"
> subnode pair, so device trees that have not been converted still
> validate.
> 
> Update the example to the subnode form, which also picks up the two
> supporting properties the subnodes need on the parent video-codec node,
> '#address-cells' and '#size-cells' of 2 and an empty "dma-ranges". Both
> are described in the common schema change.
> 
> Fixes: 41661853ae8e ("arm64: dts: qcom: sm8550: add iris DT node")
> Cc: [email protected]
> Co-developed-by: Vishnu Reddy <[email protected]>
> Signed-off-by: Vishnu Reddy <[email protected]>
> Tested-by: Daniel J Blueman <[email protected]>

Also not a valid tag.


> Signed-off-by: Vikash Garodia <[email protected]>
> ---
>  .../devicetree/bindings/media/qcom,sm8550-iris.yaml    | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/media/qcom,sm8550-iris.yaml b/Documentation/devicetree/bindings/media/qcom,sm8550-iris.yaml
> index 0400ca1bff05dcef6b742c3fbf77e38adca9f280..3d8ff5677bd4fb7f3619a95b1c5f6f9eaf39b32c 100644
> --- a/Documentation/devicetree/bindings/media/qcom,sm8550-iris.yaml
> +++ b/Documentation/devicetree/bindings/media/qcom,sm8550-iris.yaml
> @@ -98,10 +98,10 @@ required:
>    - interconnect-names
>    - resets
>    - reset-names
> -  - iommus
>    - dma-coherent
>  
>  allOf:
> +  - $ref: qcom,venus-common.yaml#
>    - if:
>        properties:
>          compatible:
> @@ -177,12 +177,24 @@ examples:
>          resets = <&gcc GCC_VIDEO_AXI0_CLK_ARES>;
>          reset-names = "bus";
>  
> -        iommus = <&apps_smmu 0x1940 0x0000>,
> -                 <&apps_smmu 0x1947 0x0000>;
>          dma-coherent;
>  
>          operating-points-v2 = <&iris_opp_table>;
>  
> +        #address-cells = <2>;
> +        #size-cells = <2>;

Drop both

Best regards,
Krzysztof