linux-kernel - Re: [PATCH v3 4/5] dt-bindings: display/msm: add stream pixel clock bindings for MST

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Message-ID: <20250718-enigmatic-grumpy-worm-64fdd0@kuoka>
Date: Fri, 18 Jul 2025 09:26:34 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Jessica Zhang <jessica.zhang@....qualcomm.com>
Cc: Abhinav Kumar <quic_abhinavk@...cinc.com>, 
	Dmitry Baryshkov <lumag@...nel.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>, 
	Abel Vesa <abel.vesa@...aro.org>, Bjorn Andersson <andersson@...nel.org>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, 
	Mahadevan <quic_mahap@...cinc.com>, Krishna Manikandan <quic_mkrishn@...cinc.com>, 
	Konrad Dybcio <konradybcio@...nel.org>, Rob Clark <robin.clark@....qualcomm.com>, 
	Abhinav Kumar <abhinav.kumar@...ux.dev>, Danila Tikhonov <danila@...xyga.com>, 
	cros-qcom-dts-watchers@...omium.org, Abhinav Kumar <abhinav.kumar@....qualcomm.com>, 
	linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org, 
	Yongxing Mou <quic_yongmou@...cinc.com>
Subject: Re: [PATCH v3 4/5] dt-bindings: display/msm: add stream pixel clock
 bindings for MST

On Thu, Jul 17, 2025 at 04:28:46PM -0700, Jessica Zhang wrote:
> From: Abhinav Kumar <quic_abhinavk@...cinc.com>
> 
> On some chipsets such as qcom,sa8775p-dp, qcom,sm8650-dp and some more,
> the display port controller can support more than one pixel stream
> (multi-stream transport).
> 
> These chipsets can support up to 4 stream pixel clocks for display port
> controller. To support MST on these platforms, add the appropriate
> stream pixel clock bindings
> 
> 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.
> 
> Note: On chipsets that do support MST, the number of streams supported
> can vary between controllers. For example, SA8775P supports 4 MST
> streams on mdss_dp0 but only 2 streams on mdss_dp1.
> 
> In addition, many chipsets depend on the "sm8350-dp" compatibility
> string but not all (ex. SM6350) support MST. Because of these reasons,
> the min/maxItem for MST-supported platforms is a range of 5-8.

Then you need to rework if:. Don't use contains for the sm8350-dp, but
list the front compatibles supporting.

> 
> Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> Signed-off-by: Jessica Zhang <jessica.zhang@....qualcomm.com>
> ---
>  .../bindings/display/msm/dp-controller.yaml        | 36 +++++++++++++++++++++-
>  .../bindings/display/msm/qcom,sa8775p-mdss.yaml    | 10 ++++--
>  .../bindings/display/msm/qcom,sar2130p-mdss.yaml   |  6 ++--
>  .../bindings/display/msm/qcom,sc7280-mdss.yaml     |  6 ++--
>  .../bindings/display/msm/qcom,sm8750-mdss.yaml     |  6 ++--
>  .../bindings/display/msm/qcom,x1e80100-mdss.yaml   |  6 ++--
>  6 files changed, 59 insertions(+), 11 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> index d8d94f62c102..2893f097df82 100644
> --- a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> +++ b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> @@ -58,20 +58,28 @@ 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 Pixel clock
> +      - description: Display Port stream 0 Pixel clock
> +      - description: Display Port stream 1 Pixel clock
> +      - description: Display Port stream 2 Pixel clock
> +      - description: Display Port stream 3 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
> +      - const: stream_2_pixel
> +      - const: stream_3_pixel
>  
>    phys:
>      maxItems: 1
> @@ -173,6 +181,32 @@ allOf:
>        required:
>          - "#sound-dai-cells"
>  
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - qcom,sa8775p-dp
> +              - qcom,sc7280-dp
> +              - qcom,sc8180x-dp
> +              - qcom,sc8280xp-dp
> +              - qcom,sc8280xp-edp
> +              - qcom,sm8150-dp
> +              - qcom,sm8350-dp
> +              - qcom,sm8650-dp
> +              - qcom,x1e80100-dp
> +    then:
> +      properties:
> +        clocks:
> +          minItems: 5
> +          maxItems: 8

This if is redundant, drop.

> +
> +    else:
> +      properties:
> +        clocks:
> +          minItems: 5
> +          maxItems: 5

Only this part has an actual effect.

Best regards,
Krzysztof