linux-kernel - Re: [PATCH v1 2/3] dt-bindings: arm: mediatek: mmsys: Add OF graph support for board path

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Message-ID: <CAGXv+5F9rfTVDExKSCF7fBKwR+HijNzFYE6+4aHKw3ZP81DG9w@mail.gmail.com>
Date: Mon, 8 Apr 2024 11:20:29 +0800
From: Chen-Yu Tsai <wenst@...omium.org>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: chunkuang.hu@...nel.org, robh@...nel.org, 
	krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org, 
	p.zabel@...gutronix.de, airlied@...il.com, daniel@...ll.ch, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de, 
	matthias.bgg@...il.com, shawn.sung@...iatek.com, yu-chang.lee@...iatek.com, 
	ck.hu@...iatek.com, jitao.shi@...iatek.com, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	linux-mediatek@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org, 
	kernel@...labora.com
Subject: Re: [PATCH v1 2/3] dt-bindings: arm: mediatek: mmsys: Add OF graph
 support for board path

On Thu, Apr 4, 2024 at 4:16 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com> wrote:
>
> Document OF graph on MMSYS/VDOSYS: this supports up to three DDP paths
> per HW instance (so potentially up to six displays for multi-vdo SoCs).
>
> The MMSYS or VDOSYS is always the first component in the DDP pipeline,
> so it only supports an output port with multiple endpoints - where each
> endpoint defines the starting point for one of the (currently three)
> possible hardware paths.
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
>  .../bindings/arm/mediatek/mediatek,mmsys.yaml | 23 +++++++++++++++++++
>  1 file changed, 23 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml
> index b3c6888c1457..90758bb5bcb1 100644
> --- a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml
> +++ b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml
> @@ -93,6 +93,29 @@ properties:
>    '#reset-cells':
>      const: 1
>
> +  port:
> +    $ref: /schemas/graph.yaml#/properties/port
> +    description:
> +      Output port node. This port connects the MMSYS/VDOSYS output to
> +      the first component of one display pipeline, for example one of
> +      the available OVL or RDMA blocks.
> +      Some MediaTek SoCs support up to three display outputs per MMSYS.
> +    properties:
> +      endpoint@0:
> +        $ref: /schemas/graph.yaml#/properties/endpoint
> +        description: Output to the primary display pipeline
> +
> +      endpoint@1:
> +        $ref: /schemas/graph.yaml#/properties/endpoint
> +        description: Output to the secondary display pipeline
> +
> +      endpoint@2:
> +        $ref: /schemas/graph.yaml#/properties/endpoint
> +        description: Output to the tertiary display pipeline
> +
> +      required:
> +        - endpoint@0
> +

Technically the mmsys device serves as an glue layer for the display
pipeline, providing things like clock control and signal routing; the
device itself is not part of the pipeline, and probably shouldn't be
part of the graph?

ChenYu

>  required:
>    - compatible
>    - reg
> --
> 2.44.0
>