Re: [PATCH v2 01/12] dt-bindings: media: qcom,venus: Add context bank subnodes to common schema

[Dmitry Baryshkov]

On Fri, Jul 31, 2026 at 11:52:16PM +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 inside the low 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
> 
>  
> +  dma-ranges: true
> +
> +  '#address-cells':
> +    const: 2
> +
> +  '#size-cells':
> +    const: 2

This would conflict with the 32-bit addressed Venus nodes (and it will
also break examples). So both should be just 'true'

>  
> +oneOf:
> +  - required:
> +      - iommus
> +  - required:
> +      - non-pixel
> +      - pixel

- #address-cells
- #size-cells
- dma-ranges

> +
>  additionalProperties: true
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry