linux-kernel - Re: [PATCH v4 1/2] dt-bindings: it6505: add properties to restrict output bandwidth

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Message-ID: <Y0r7tplRZbtiX+U6@pendragon.ideasonboard.com>
Date:   Sat, 15 Oct 2022 21:28:06 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     allen.chen@....com.tw
Cc:     robh@...nel.org, treapking@...omium.org, Jau-Chih.Tseng@....com.tw,
        Kenneth.Hung@....com.tw, Hermes.Wu@....com.tw,
        andrzej.hajda@...el.com, narmstrong@...libre.com,
        robert.foss@...aro.org, jonas@...boo.se, jernej.skrabec@...il.com,
        airlied@...ux.ie, daniel@...ll.ch,
        krzysztof.kozlowski+dt@...aro.org, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/2] dt-bindings: it6505: add properties to restrict
 output bandwidth

Hello,

On Fri, Oct 14, 2022 at 03:28:31AM +0000, allen.chen@....com.tw wrote:
> On Friday, October 14, 2022 3:20 AM, Rob Herring wrote:
> > On Thu, Oct 13, 2022 at 02:05:45PM +0300, Laurent Pinchart wrote:
> > > On Thu, Oct 13, 2022 at 06:51:13PM +0800, allen wrote:
> > > > From: allen chen <allen.chen@....com.tw>
> > > > 
> > > > Add properties to restrict dp output data-lanes and clock.
> > > > 
> > > > Signed-off-by: Pin-Yen Lin <treapking@...omium.org>
> > > > Signed-off-by: Allen Chen <allen.chen@....com.tw>
> > > > ---
> > > >  .../bindings/display/bridge/ite,it6505.yaml   | 43 +++++++++++++++++++
> > > >  1 file changed, 43 insertions(+)
> > > > 
> > > > diff --git a/Documentation/devicetree/bindings/display/bridge/ite,it6505.yaml b/Documentation/devicetree/bindings/display/bridge/ite,it6505.yaml
> > > > index 833d11b2303a7..f2c3d1d10359e 100644
> > > > --- a/Documentation/devicetree/bindings/display/bridge/ite,it6505.yaml
> > > > +++ b/Documentation/devicetree/bindings/display/bridge/ite,it6505.yaml
> > > > @@ -52,10 +52,51 @@ properties:
> > > >      maxItems: 1
> > > >      description: extcon specifier for the Power Delivery
> > > >  
> > > > +  data-lanes:
> > > > +    oneOf:
> > > > +      - minItems: 1
> > > > +        maxItems: 1
> > > > +        uniqueItems: true
> > > > +        items:
> > > > +          enum:
> > > > +            - 0
> > > > +            - 1
> > > > +        description: For one lane operation.
> > > > +
> > > > +      - minItems: 2
> > > > +        maxItems: 2
> > > > +        uniqueItems: true
> > > > +        items:
> > > > +          enum:
> > > > +            - 0
> > > > +            - 1
> > > > +        description: For two lanes operation.
> > > > +
> > > > +      - minItems: 4
> > > > +        maxItems: 4
> > > > +        uniqueItems: true
> > > > +        items:
> > > > +          enum:
> > > > +            - 0
> > > > +            - 1
> > > > +            - 2
> > > > +            - 3
> > > > +        description: For four lanes operation.
> > > 
> > > The data lanes should be in the output endpoint. If there's no output 
> > > port, one should be added.
> 
> ==> In this dt-binding, our output point is "extcon" so doesn't have output endpoint.
> I don't know how to add the endpoint.
> If need to add the endpoint to this dt-binding, what is your recommend about adding the endpoint?

You will also need to add a port to the USB-C connector. Then endpoints
can be added to connect the two.

> By the way, Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> said
> we could put "data-lanes" here.

If I read him correctly, Krzysztof said we have a standard property for
the data lanes (and that's true, we do), but I don't think he implied it
could be put outside of the endpoint (Krzysztof, please correct me if
I'm wrong).

> > > > +
> > > >    port:
> > > >      $ref: /schemas/graph.yaml#/properties/port
> > 
> > To fix the error, this must be:
> > 
> > $ref: /schemas/graph.yaml#/$defs/port-base
> > unevaluatedProperties: false
> > 
> > > >      description: A port node pointing to DPI host port node
> > > >  
> > > > +    properties:
> > > > +      endpoint:
> > > > +        $ref: /schemas/graph.yaml#/$defs/endpoint-base
> > > > +
> > > > +        properties:
> > > > +          link-frequencies:
> > > > +            minItems: 1
> > > > +            maxItems: 1
> > > > +            description: Allowed max link frequencies in Hz.
> > > > +
> > > >  required:
> > > >    - compatible
> > > >    - ovdd-supply
> > > > @@ -84,10 +125,12 @@ examples:
> > > >              pwr18-supply = <&it6505_pp18_reg>;
> > > >              reset-gpios = <&pio 179 1>;
> > > >              extcon = <&usbc_extcon>;
> > > > +            data-lanes = <0 1>;
> > > >  
> > > >              port {
> > > >                  it6505_in: endpoint {
> > > >                      remote-endpoint = <&dpi_out>;
> > > > +                    link-frequencies = /bits/ 64 <150000000>;
> > > >                  };
> > > >              };
> > > >          };

-- 
Regards,

Laurent Pinchart