Re: [RFC PATCH 01/11] dt-bindings: media: qcom,sm8550-iris: Add vpu sub nodes

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

On 7/10/2026 9:23 PM, Dmitry Baryshkov wrote:
> On Fri, Jul 10, 2026 at 11:32:20AM +0530, Vikash Garodia wrote:
>>
>> On 7/9/2026 6:20 PM, Dmitry Baryshkov wrote:
>>> On Thu, Jul 09, 2026 at 06:05:47PM +0530, Vikash Garodia wrote:
>>>> VPU hardwares have a limitation where VPU streams are associated with
>>>> dedicated addressable address range, as illustrated below
>>>>
>>>>       +-----------------------------------------------------------+
>>>>       | Stream A reserved region (600 MB)                         |
>>>>       | 0x00000000 - 0x25800000                                   |
>>>>       +-----------------------------------------------------------+
>>>>       | Stream B reserved region (3.5 GB)                         |
>>>>       | 0x00000000 - 0xe0000000                                   |
>>>>       +-----------------------------------------------------------+
>>>>       | Other reserved regions                                    |
>>>>       +-----------------------------------------------------------+
>>>>
>>>> Mapping a stream outside its expected range can cause unintended
>>>> behavior, including device crashes, as reported at:
>>>> https://gitlab.freedesktop.org/drm/msm/-/work_items/100
>>>>
>>>> To address this limitation, the subset of stream/s are now represented as
>>>> sub nodes, so that they can be associated to the respective addressable
>>>> range.
>>>> The limitation could be exposed when running usecase like concurrent
>>>> video sessions. The binding have been validated with higher concurrent
>>>> sessions across the SOCs supported under this schema.
>>>>
>>>> Co-developed-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
>>>> Signed-off-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
>>>> Signed-off-by: Vikash Garodia <vikash.garodia@oss.qualcomm.com>
>>>> ---
>>>>    .../bindings/media/qcom,sm8550-iris.yaml           | 66 +++++++++++++++++++++-
>>>>    1 file changed, 63 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..bf4d24ce90bd38666704274390b98be450f708c0 100644
>>>> --- a/Documentation/devicetree/bindings/media/qcom,sm8550-iris.yaml
>>>> +++ b/Documentation/devicetree/bindings/media/qcom,sm8550-iris.yaml
>>>> @@ -91,6 +91,51 @@ properties:
>>>>      opp-table:
>>>>        type: object
>>>> +  '#address-cells':
>>>> +    const: 2
>>>> +
>>>> +  '#size-cells':
>>>> +    const: 2
>>>> +
>>>> +  non-pixel:
>>>> +    type: object
>>>> +    description:
>>>> +      Non pixel context bank is needed when video hardware have distinct iommus for non pixel
>>>> +      buffers. Non pixel buffers are compressed and internal buffers.
>>>> +    properties:
>>>> +      iommus:
>>>> +        maxItems: 1
>>>> +      memory-region:
>>>> +        maxItems: 1
>>>> +    required:
>>>> +      - iommus
>>>> +      - memory-region
>>>> +    additionalProperties: false
>>>> +
>>>> +  pixel:
>>>> +    type: object
>>>> +    description:
>>>> +      Pixel context bank is needed when video hardware have distinct iommus for pixel buffers.
>>>> +      Pixel buffers are uncompressed buffers.
>>>> +    properties:
>>>> +      iommus:
>>>> +        maxItems: 1
>>>> +    required:
>>>> +      - iommus
>>>> +    additionalProperties: false
>>>> +
>>>> +  firmware:
>>>> +    type: object
>>>> +    description:
>>>> +      Firmware context bank represents the firmware processing domain of the VPU. Required to boot
>>>> +      VPU when no hypervisor is present.
>>>> +    properties:
>>>> +      iommus:
>>>> +        maxItems: 1
>>>> +    required:
>>>> +      - iommus
>>>> +    additionalProperties: false
>>>> +
>>>>    required:
>>>>      - compatible
>>>>      - power-domain-names
>>>> @@ -98,9 +143,15 @@ required:
>>>>      - interconnect-names
>>>>      - resets
>>>>      - reset-names
>>>> -  - iommus
>>>>      - dma-coherent
>>>> +oneOf:
>>>> +  - required:
>>>> +      - iommus
>>>> +  - required:
>>>> +      - non-pixel
>>>> +      - pixel
>>>> +
>>>>    allOf:
>>>>      - if:
>>>>          properties:
>>>> @@ -177,12 +228,21 @@ 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>;
>>>
>>> I think you need "ranges;" here. Also an empty line before the subnodes.
>>
>> Could you please elaborate on what would be the use of "ranges;" in this
>> case ?
> 
> That the subblock has the same address space as the parent. I might be
> completely wrong here.

Yes, i explored with the same definition of "ranges", but could not see 
a use of it in our case. I am dropping this for now, unless there are 
suggestion on this on applicability of it in this case.

> 
>>
>>>
>>>> +        iris_non_pixel: non-pixel {
>>>
>>> Drop useless labels.
>>
>> Ack, labels can be dropped from schema.
>>
>>>
>>>> +            iommus = <&apps_smmu 0x1940 0x0000>;
>>>> +            memory-region = <&iris_resv>;
>>>> +        };
>>>> +
>>>> +        iris_pixel: pixel {
>>>> +            iommus = <&apps_smmu 0x1947 0x0000>;
>>>> +        };
>>>> +
>>>>            iris_opp_table: opp-table {
>>>>                compatible = "operating-points-v2";
>>>>
>>>> -- 
>>>> 2.34.1
>>>>
>>>
>>
>> Regards,
>> Vikash
>>
>