Re: [PATCH v5 01/13] dt-bindings: media: qcom,venus: Add context bank subnodes to common schema

[Zhangfei Gao]

On Thu, Oct 8, 2026 at 5:34 PM Vikash Garodia
<vikash.garodia@xxxxxxxxxxxxxxxx> wrote:
>
>
> On 10/8/2026 12:16 PM, Zhangfei Gao wrote:
> > On Sat, Sep 26, 2026 at 2:38 PM Vikash Garodia
> > <vikash.garodia@xxxxxxxxxxxxxxxx> 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
> >> cannot address the low 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 restricts a
> >> non-pixel buffer to avoid 0 to 600MB. 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
> >>
> >> Given that the address range restriction is for specific VPU stream, it
> >> should be ideally be moved to that stream. To achieve the same, a subset
> >> of streams is now represented as subnodes, so that each can be
> >> associated with its respective addressable range. The design was
> >> discussed and agreed by mainatiners here
> >> https://lore.kernel.org/all/c7b956a9-d3e8-4e18-b780-5d08f5cd2ca1@xxxxxxxxxx
> >>
> >> In the past, this limitation was addressed with an iommu-map approach,
> >> with the iris driver dynamically creating the devices. That approach was
> >> later concluded to be a hack to avoid having subnodes, and was NAKed by
> >> the iommu maintainers. It was discussed in detail here:
> >> https://lore.kernel.org/all/c7b956a9-d3e8-4e18-b780-5d08f5cd2ca1@xxxxxxxxxx/
> >>
> >> "iommu-ranges" on the subnode describes the *allowed* IOVA range that
> >> stream is allowed to use, so the IOVA is allocated from the specified
> >> range only. Define all the possible subnodes so as to describe all the
> >> VPU hardware iommu interfaces, both secure as well as non secure.
> >>
> >> address-cells, size-cells and dma-ranges declares the 1:1 DMA
> >> translation into the parent.
> >>
> >> The parent "iommus" is kept as an alternative via "oneOf", so platforms
> >> that have not been converted to subnodes still validate. New platforms
> >> should use the subnode form.
> >>
> >> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxxxxx>
> >> Signed-off-by: Vikash Garodia <vikash.garodia@xxxxxxxxxxxxxxxx>
> >> ---
> >>   .../bindings/media/qcom,sc7180-venus.yaml          | 15 ----
> >>   .../bindings/media/qcom,venus-common.yaml          | 97 ++++++++++++++++++++++
> >>   2 files changed, 97 insertions(+), 15 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/media/qcom,sc7180-venus.yaml b/Documentation/devicetree/bindings/media/qcom,sc7180-venus.yaml
> >> index b21bed314848480b82153e49602f0b19e08e7335..bfd8b1ad473128c974bce84639cb0aff59d8c2cc 100644
> >> --- a/Documentation/devicetree/bindings/media/qcom,sc7180-venus.yaml
> >> +++ b/Documentation/devicetree/bindings/media/qcom,sc7180-venus.yaml
> >> @@ -91,21 +91,6 @@ properties:
> >>       deprecated: true
> >>       additionalProperties: false
> >>
> >> -  video-firmware:
> >> -    type: object
> >> -    additionalProperties: false
> >> -
> >> -    description: |
> >> -      Firmware subnode is needed when the platform does not
> >> -      have TrustZone.
> >> -
> >> -    properties:
> >> -      iommus:
> >> -        maxItems: 1
> >> -
> >> -    required:
> >> -      - iommus
> >> -
> >>   required:
> >>     - compatible
> >>     - power-domain-names
> >> diff --git a/Documentation/devicetree/bindings/media/qcom,venus-common.yaml b/Documentation/devicetree/bindings/media/qcom,venus-common.yaml
> >> index 59a3fde846d2196ab1e4588eb396012ba6860712..68d5e592a028c5eecde04ce72cd5ae6815ba5c82 100644
> >> --- a/Documentation/devicetree/bindings/media/qcom,venus-common.yaml
> >> +++ b/Documentation/devicetree/bindings/media/qcom,venus-common.yaml
> >> @@ -47,6 +47,93 @@ properties:
> >>       minItems: 1
> >>       maxItems: 4
> >>
> >> +  '#address-cells':
> >> +    const: 1
> >> +
> >> +  '#size-cells':
> >> +    const: 1
> >> +
> >> +  dma-ranges:
> >> +    maxItems: 1
> >> +
> >> +  non-pixel:
> >> +    type: object
> >> +    description:
> >> +      Context bank for VPU non-pixel buffers, including compressed and internal buffers.
> >> +    additionalProperties: false
> >> +
> >> +    properties:
> >> +      iommus:
> >> +        maxItems: 1
> >> +      iommu-ranges:
> >> +        maxItems: 1
> >> +    required:
> >> +      - iommus
> >> +      - iommu-ranges
> >> +
> >> +  pixel:
> >> +    type: object
> >> +    description:
> >> +      Context bank for VPU pixel buffers containing uncompressed video data.
> >> +    additionalProperties: false
> >> +
> >> +    properties:
> >> +      iommus:
> >> +        maxItems: 1
> >> +    required:
> >> +      - iommus
> >> +
> >> +  video-firmware:
> >> +    type: object
> >> +    description:
> >> +      Context bank for the VPU firmware processing domain.
> >> +    additionalProperties: false
> >> +
> >> +    properties:
> >> +      iommus:
> >> +        maxItems: 1
> >> +    required:
> >> +      - iommus
> >> +
> >> +  secure-non-pixel:
> >> +    type: object
> >> +    description:
> >> +      Context bank for VPU secure non-pixel buffers.
> >> +    additionalProperties: false
> >> +
> >> +    properties:
> >> +      iommus:
> >> +        maxItems: 1
> >> +      iommu-ranges:
> >> +        maxItems: 1
> >> +    required:
> >> +      - iommus
> >> +      - iommu-ranges
> >> +
> >> +  secure-pixel:
> >> +    type: object
> >> +    description:
> >> +      Context bank for VPU secure pixel buffers containing uncompressed video data.
> >> +    additionalProperties: false
> >> +
> >> +    properties:
> >> +      iommus:
> >> +        maxItems: 1
> >> +    required:
> >> +      - iommus
> >> +
> >> +  secure-bitstream:
> >> +    type: object
> >> +    description:
> >> +      Context bank for VPU secure bitstream buffers containing compressed video data.
> >> +    additionalProperties: false
> >> +
> >> +    properties:
> >> +      iommus:
> >> +        maxItems: 1
> >> +    required:
> >> +      - iommus
> >> +
> >>   required:
> >>     - reg
> >>     - clocks
> >> @@ -55,4 +142,14 @@ required:
> >>     - memory-region
> >>     - power-domains
> >>
> >> +oneOf:
> >> +  - required:
> >> +      - iommus
> >> +  - required:
> >> +      - '#address-cells'
> >> +      - '#size-cells'
> >> +      - dma-ranges
> >> +      - non-pixel
> >> +      - pixel
> >> +
> >>   additionalProperties: true
> >>
> > Got this warning:
> > arch/arm64/boot/dts/qcom/nord-rrd.dtb: non-pixel: iommu-ranges:
> > b'%\x80\x00\x00\xda`\x00\x00' is not of type 'object', 'integer',
> > 'array', 'boolean', 'null'
> > arch/arm64/boot/dts/qcom/nord-ride-embedded.dtb: non-pixel:
> > iommu-ranges: b'%\x80\x00\x00\xda`\x00\x00' is not of type 'object',
> > 'integer', 'array', 'boolean', 'null'
> >
>
> You have not picked the latest dt schema. Please go through the cover
> letter where a PR is mentioned, please pull that or validate against
> latest schema.

Yes, with the latest dt schema, the check passes, thanks.