[PATCH 3/4] dt-bindings: display/msm: add stream 1 pixel clock binding

[Abhinav Kumar]

On 5/7/2025 11:18 PM, Krzysztof Kozlowski wrote:
> On 23/04/2025 04:46, Abhinav Kumar wrote:
>> Hi Krzysztof
>>
>> On 12/3/2024 12:04 AM, Krzysztof Kozlowski wrote:
>>> On 03/12/2024 04:31, Abhinav Kumar wrote:
>>>> On some chipsets the display port controller can support more
>>>
>>> Which chipsets?
>>>
>>
>>   From the current list of chipsets which support DP, the following can
>> support more than one stream.
>>
>> qcom,sa8775p-dp
>> qcom,sc7280-dp
>> qcom,sc8180x-dp
>> qcom,sc8280xp-dp
>> qcom,sm8350-dp
>> qcom,sm8650-dp
>> qcom,sm8550-dp
>> qcom,sm8450-dp
>> qcom,sm8250-dp
>> qcom,sm8150-dp
>>
>> So do you also want all of these to be added in the same if block as
>> qcom,sa8775p-dp?
> 
> That was talk in 2024. Entire context is gone if you reply after three
> months. I do not have even that emails in my inbox anymore.
> 
> Probably I expected commit msg to mention at least some, so everyone
> knows which chipsets are affected here and one can verify the statements
> from commit msg.
> 

Sure will do.

>>
>>>> than one pixel stream (multi-stream transport). To support MST
>>>> on such chipsets, add the binding for stream 1 pixel clock for
>>>> display port controller. Since this mode is not supported on all
>>>> chipsets, add exception rules and min/max items to clearly mark
>>>> which chipsets support only SST mode (single stream) and which ones
>>>> support MST.
>>>>
>>>> Signed-off-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
>>>> ---
>>>>    .../bindings/display/msm/dp-controller.yaml        | 32 ++++++++++++++++++++++
>>>>    .../bindings/display/msm/qcom,sa8775p-mdss.yaml    |  9 ++++--
>>>>    2 files changed, 38 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
>>>> index 9fe2bf0484d8..650d19e58277 100644
>>>> --- a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
>>>> +++ b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
>>>> @@ -50,30 +50,38 @@ properties:
>>>>        maxItems: 1
>>>>    
>>>>      clocks:
>>>> +    minItems: 5
>>>>        items:
>>>>          - description: AHB clock to enable register access
>>>>          - description: Display Port AUX clock
>>>>          - description: Display Port Link clock
>>>>          - description: Link interface clock between DP and PHY
>>>>          - description: Display Port stream 0 Pixel clock
>>>> +      - description: Display Port stream 1 Pixel clock
>>>>    
>>>>      clock-names:
>>>> +    minItems: 5
>>>>        items:
>>>>          - const: core_iface
>>>>          - const: core_aux
>>>>          - const: ctrl_link
>>>>          - const: ctrl_link_iface
>>>>          - const: stream_pixel
>>>> +      - const: stream_1_pixel
>>>>    
>>>>      assigned-clocks:
>>>> +    minItems: 2
>>>>        items:
>>>>          - description: link clock source
>>>>          - description: stream 0 pixel clock source
>>>> +      - description: stream 1 pixel clock source
>>>>    
>>>>      assigned-clock-parents:
>>>> +    minItems: 2
>>>>        items:
>>>>          - description: Link clock PLL output provided by PHY block
>>>>          - description: Stream 0 pixel clock PLL output provided by PHY block
>>>> +      - description: Stream 1 pixel clock PLL output provided by PHY block
>>>>    
>>>>      phys:
>>>>        maxItems: 1
>>>> @@ -175,6 +183,30 @@ allOf:
>>>>          required:
>>>>            - "#sound-dai-cells"
>>>>    
>>>
>>> Missing if: narrowing this to 5 items for other devices.
>>>
>>
>> OR would an else be better?
> 
> Usually not, although depends how this binding is written.
> 

Ok, let me try it.

> 
>>
>> +    else:
>> +      properties:
>> +        clocks:
>> +          maxItems: 5
>> +        clock-names:
>> +          items:
>> +            - const: core_iface
>> +            - const: core_aux
>> +            - const: ctrl_link
>> +            - const: ctrl_link_iface
>> +            - const: stream_pixel
>>
>>>> +  - if:
>>>> +      properties:
>>>> +        compatible:
>>>> +          contains:
>>>> +            enum:
>>>> +              - qcom,sa8775p-dp
>>>> +
>>>> +    then:
>>>> +      properties:
>>>> +        clocks:
>>>
>>> Missing minItems, otherwise it is pointless.
>>>
>>
>> I thought that since I have already specified the minItems as 5
>> in the clocks in the section above, I need to specify only the maxItems
>> here?
> 
> No, you need explicit constraints here.
> 

Ack

> 
> 
> Best regards,
> Krzysztof