linux-kernel - Re: [PATCH 4/7] dt-bindings: drm/bridge: anx7625: Add mode-switch support

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Date:   Wed, 8 Jun 2022 17:08:12 +0000
From:   Prashant Malani <pmalani@...omium.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        bleung@...omium.org, swboyd@...omium.org,
        heikki.krogerus@...ux.intel.com,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        José Expósito <jose.exposito89@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Maxime Ripard <maxime@...no.tech>,
        Neil Armstrong <narmstrong@...libre.com>,
        Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>, Pin-Yen Lin <treapking@...omium.org>,
        Robert Foss <robert.foss@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Xin Ji <xji@...logixsemi.com>
Subject: Re: [PATCH 4/7] dt-bindings: drm/bridge: anx7625: Add mode-switch
 support

Hi Krzysztof,

Thank you for looking at the patch.

On Jun 08 11:24, Krzysztof Kozlowski wrote:
> On 07/06/2022 21:00, Prashant Malani wrote:
> > Analogix 7625 can be used in systems to switch USB Type-C DisplayPort
> > alternate mode lane traffic between 2 Type-C ports.
> > 
> > Update the binding to accommodate this usage by introducing a switch
> > property.
> > 
> > Signed-off-by: Prashant Malani <pmalani@...omium.org>
> > ---
> >  .../display/bridge/analogix,anx7625.yaml      | 56 +++++++++++++++++++
> >  1 file changed, 56 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/display/bridge/analogix,anx7625.yaml b/Documentation/devicetree/bindings/display/bridge/analogix,anx7625.yaml
> > index 35a48515836e..7e1f655ddfcc 100644
> > --- a/Documentation/devicetree/bindings/display/bridge/analogix,anx7625.yaml
> > +++ b/Documentation/devicetree/bindings/display/bridge/analogix,anx7625.yaml
> > @@ -105,6 +105,26 @@ properties:
> >        - port@0
> >        - port@1
> >  
> > +  switches:
> > +    type: object
> > +    description: Set of switches controlling DisplayPort traffic on
> > +      outgoing RX/TX lanes to Type C ports.
> > +
> > +    properties:
> > +      switch:
> 
> You allow only one switch with such schema, so no need for "switches"...

See below comment (summary: we'd like to allow 1 or 2 switches).
> 
> > +        $ref: /schemas/usb/typec-switch.yaml#
> > +        maxItems: 2
> 
> Are you sure this works? what are you limiting here with maxItems? I
> think you wanted patternProperties...

Yeah, I might not have used the DT syntax correctly here.
What I'm aiming for is:
"switches" should can contain 1 or 2 "switch" nodes.
2 is the maximum (limitation of the hardware).

> 
> > +
> > +        properties:
> > +          reg:
> > +            maxItems: 1
> > +
> > +        required:
> > +          - reg
> > +
> > +    required:
> > +      - switch@0
> 
> This does not match the property.
> 
> You also need unevaluatedProperties:false

Ack, will update this in the next version.

> 
> 
> > +
> >  required:
> >    - compatible
> >    - reg
> > @@ -167,5 +187,41 @@ examples:
> >                      };
> >                  };
> >              };
> > +            switches {
> > +                #address-cells = <1>;
> > +                #size-cells = <0>;
> > +                switch@0 {
> > +                    compatible = "typec-switch";
> > +                    reg = <0>;
> > +                    mode-switch;
> > +
> > +                    ports {
> > +                        #address-cells = <1>;
> > +                        #size-cells = <0>;
> > +                        port@0 {
> > +                            reg = <0>;
> > +                            anx_typec0: endpoint {
> > +                              remote-endpoint = <&typec_port0>;
> 
> Messed up indentation. Your previous patch should also switch to 4-space
> as recommended by schema coding style.

Sorry about that, will fix up the indentation in the next version.

> 
> > +                            };
> > +                        };
> > +                    };
> > +                };
> > +                switch@1 {
> > +                    compatible = "typec-switch";
> > +                    reg = <1>;
> > +                    mode-switch;
> > +
> > +                    ports {
> > +                        #address-cells = <1>;
> > +                        #size-cells = <0>;
> > +                        port@0 {
> > +                            reg = <0>;
> > +                            anx_typec1: endpoint {
> > +                              remote-endpoint = <&typec_port1>;
> 
> Ditto.
> 
> > +                            };
> > +                        };
> > +                    };
> > +                };
> > +            };
> >          };
> >      };
> 
> 
> Best regards,
> Krzysztof