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

["Rob Herring (Arm)" <robh@kernel.org>]

On Fri, 31 Jul 2026 23:52:17 +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: stable@vger.kernel.org
> Co-developed-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
> Signed-off-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
> Tested-by: Daniel J Blueman <daniel@quora.org>
> Signed-off-by: Vikash Garodia <vikash.garodia@oss.qualcomm.com>
> ---
>  .../devicetree/bindings/media/qcom,sm8550-iris.yaml    | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
Documentation/devicetree/bindings/media/qcom,sm8550-iris.example.dts:67.13-24: Warning (dma_ranges_format): /example-0/video-codec@aa00000:dma-ranges: empty "dma-ranges" property but its #address-cells (2) differs from /example-0 (1)
Documentation/devicetree/bindings/media/qcom,sm8550-iris.example.dts:67.13-24: Warning (dma_ranges_format): /example-0/video-codec@aa00000:dma-ranges: empty "dma-ranges" property but its #size-cells (2) differs from /example-0 (1)

doc reference errors (make refcheckdocs):

See https://patchwork.kernel.org/project/devicetree/patch/20260731-vpu_iommu_iova_handling-v2-2-da52b5228dbd@oss.qualcomm.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.