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

[Vikash Garodia <vikash.garodia@oss.qualcomm.com>]

On 10/8/2026 12:16 PM, Zhangfei Gao wrote:
> On Sat, Sep 26, 2026 at 2:38 PM Vikash Garodia
> <vikash.garodia@oss.qualcomm.com> 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@kernel.org
>>
>> 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@kernel.org/
>>
>> "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@oss.qualcomm.com>
>> Signed-off-by: Vikash Garodia <vikash.garodia@oss.qualcomm.com>
>> ---
>>   .../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.

Regards,
Vikash