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Date:   Tue, 20 Jun 2023 09:37:43 -0600
From:   Rob Herring <robh@kernel.org>
To:     Alexander Stein <alexander.stein@ew.tq-group.com>
Cc:     andrzej.hajda@intel.com, neil.armstrong@linaro.org,
        robert.foss@linaro.org, Laurent.pinchart@ideasonboard.com,
        jonas@kwiboo.se, jernej.skrabec@gmail.com, airlied@gmail.com,
        daniel@ffwll.ch, krzysztof.kozlowski+dt@linaro.org,
        shawnguo@kernel.org, s.hauer@pengutronix.de, festevam@gmail.com,
        vkoul@kernel.org, dri-devel@lists.freedesktop.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, linux-phy@lists.infradead.org,
        oliver.brown@nxp.com, Sandor.yu@nxp.com, linux-imx@nxp.com,
        kernel@pengutronix.de
Subject: Re: [PATCH v6 2/8] dt-bindings: display: bridge: Add Cadence
 MHDP8501 HDMI and DP
Message-ID: <20230620153743.GA3637514-robh@kernel.org>
References: <cover.1686729444.git.Sandor.yu@nxp.com>
 <8687f2221299b120e12f29fdccf264e120227bd7.1686729444.git.Sandor.yu@nxp.com>
 <3439354.PYKUYFuaPT@steina-w>
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On Fri, Jun 16, 2023 at 11:31:43AM +0200, Alexander Stein wrote:
> Hi Sandor,
> 
> Am Donnerstag, 15. Juni 2023, 03:38:12 CEST schrieb Sandor Yu:
> > Add bindings for Cadence MHDP8501 DisplayPort and HDMI driver.
> > 
> > Signed-off-by: Sandor Yu <Sandor.yu@nxp.com>
> > ---
> >  .../display/bridge/cdns,mhdp8501.yaml         | 105 ++++++++++++++++++
> >  1 file changed, 105 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/display/bridge/cdns,mhdp8501.yaml
> > 
> > diff --git
> > a/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8501.yaml
> > b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8501.yaml new
> > file mode 100644
> > index 000000000000..a54756815e6f
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8501.yaml
> > @@ -0,0 +1,105 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/display/bridge/cdns,mhdp8501.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Cadence MHDP8501 Displayport bridge
> > +
> > +maintainers:
> > +  - Sandor Yu <Sandor.yu@nxp.com>
> > +
> > +description:
> > +  The Cadence MHDP8501 Displayport/HDMI TX interface.
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - cdns,mhdp8501-dp
> > +      - cdns,mhdp8501-hdmi
> > +      - fsl,imx8mq-mhdp8501-dp
> > +      - fsl,imx8mq-mhdp8501-hdmi
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    maxItems: 1
> > +    description: MHDP8501 DP/HDMI APB clock.
> > +
> > +  phys:
> > +    maxItems: 1
> > +
> > +  interrupts:
> > +    items:
> > +      - description: Hotplug cable plugin.
> > +      - description: Hotplug cable plugout.
> > +
> > +  interrupt-names:
> > +    items:
> > +      - const: plug_in
> > +      - const: plug_out
> > +
> > +  ports:
> > +    $ref: /schemas/graph.yaml#/properties/ports
> > +
> > +    properties:
> > +      port@0:
> > +        $ref: /schemas/graph.yaml#/properties/port
> > +        description:
> > +          Input port from display controller output.
> > +      port@1:
> > +        $ref: /schemas/graph.yaml#/properties/port
> > +        description:
> > +          Output port to DP/HDMI connector.
> > +
> > +    required:
> > +      - port@0
> > +      - port@1
> 
> You mark these ports as required, but apparently the drivers do not use them, 
> AFAICT. E.g. missing port@1 is not resulting in an error, at lease for HDMI 
> one.

A connector node should be required whether a particular OS requires it 
or not. The bindings without predate defining a connector node.

Rob