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

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Message-ID: <39f8e20a-e8c3-4625-abb1-9f35f416705d@kernel.org>
Date: Tue, 3 Dec 2024 09:04:39 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>, Rob Clark
 <robdclark@...il.com>, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
 Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Kuogee Hsieh <quic_khsieh@...cinc.com>,
 Mahadevan <quic_mahap@...cinc.com>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] dt-bindings: display/msm: add stream 1 pixel clock
 binding

On 03/12/2024 04:31, Abhinav Kumar wrote:
> On some chipsets the display port controller can support more

Which chipsets?

> 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@...cinc.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.

> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - qcom,sa8775p-dp
> +
> +    then:
> +      properties:
> +        clocks:

Missing minItems, otherwise it is pointless.

> +          maxItems: 6
> +        clock-names:
> +          items:
> +            - const: core_iface
> +            - const: core_aux
> +            - const: ctrl_link
> +            - const: ctrl_link_iface
> +            - const: stream_pixel
> +            - const: stream_1_pixel
> +        assigned-clocks:
> +          maxItems: 3

Missing minItems... or just drop, it's not accurate or not even correct.
I can assign 4 clocks, why not? Or rather: why do you stop users from
assigning 4 clocks?


> +        assigned-clock-parents:
> +          maxItems: 3
> +
>  additionalProperties: false



Best regards,
Krzysztof