Re: [PATCH 05/22] dt-bindings: media: sun6i-a31-csi: Add MIPI CSI-2 input port

[Paul Kocialkowski <paul.kocialkowski@bootlin.com>]

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Hi,

On Mon 13 Sep 21, 10:09, Maxime Ripard wrote:
> On Fri, Sep 10, 2021 at 08:41:30PM +0200, Paul Kocialkowski wrote:
> > The A31 CSI controller supports two distinct input interfaces:
> > parallel and an external MIPI CSI-2 bridge. The parallel interface
> > is often connected to a set of hardware pins while the MIPI CSI-2
> > bridge is an internal FIFO-ish link. As a result, these two inputs
> > are distinguished as two different ports.
> > 
> > Note that only one of the two may be present on a controller instance.
> > For example, the V3s has one controller dedicated to MIPI-CSI2 and one
> > dedicated to parallel.
> > 
> > Update the binding with an explicit ports node that holds two distinct
> > port nodes: one for parallel input and one for MIPI CSI-2.
> > 
> > This is backward-compatible with the single-port approach that was
> > previously taken for representing the parallel interface port, which
> > stays enumerated as fwnode port 0.
> > 
> > Note that additional ports may be added in the future, especially to
> > support feeding the CSI controller's output to the ISP.
> > 
> > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > Reviewed-by: Rob Herring <robh@kernel.org>
> > Acked-by: Maxime Ripard <mripard@kernel.org>
> > ---
> >  .../media/allwinner,sun6i-a31-csi.yaml        | 75 +++++++++++++++----
> >  1 file changed, 62 insertions(+), 13 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-csi.yaml b/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-csi.yaml
> > index 8b568072a069..f4a686b77a38 100644
> > --- a/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-csi.yaml
> > +++ b/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-csi.yaml
> > @@ -61,6 +61,49 @@ properties:
> >  
> >      additionalProperties: false
> >  
> > +  ports:
> > +    $ref: /schemas/graph.yaml#/properties/ports
> > +
> > +    properties:
> > +      port@0:
> > +        $ref: /schemas/graph.yaml#/$defs/port-base
> > +        description: Parallel input port, connect to a parallel sensor
> > +
> > +        properties:
> > +          reg:
> > +            const: 0
> > +
> > +          endpoint:
> > +            $ref: video-interfaces.yaml#
> > +            unevaluatedProperties: false
> > +
> > +            properties:
> > +              bus-width:
> > +                enum: [ 8, 10, 12, 16 ]
> > +
> > +              pclk-sample: true
> > +              hsync-active: true
> > +              vsync-active: true
> > +
> > +            required:
> > +              - bus-width
> > +
> > +        additionalProperties: false
> 
> You don't have to duplicate the entire definition there, you can just
> reference port:
> 
> $ref: #/properties/port

And that would reference the local (previous) definition of the port node?
Sounds like a good thing indeed.

> > +      port@1:
> > +        $ref: /schemas/graph.yaml#/$defs/port-base
> > +        description: MIPI CSI-2 bridge input port
> > +
> > +        properties:
> > +          reg:
> > +            const: 1
> > +
> > +          endpoint:
> > +            $ref: video-interfaces.yaml#
> > +            unevaluatedProperties: false
> > +
> > +        additionalProperties: false
> > +
> 
> port@0 is required?

It shouldn't be required. Does that call for a change here?

> And at the top-level, either ports or port are required too

Yes I guess that is true. Should that be a required+oneOf type of thing?

> >  required:
> >    - compatible
> >    - reg
> > @@ -89,19 +132,25 @@ examples:
> >                        "ram";
> >          resets = <&ccu RST_BUS_CSI>;
> >  
> > -        port {
> > -            /* Parallel bus endpoint */
> > -            csi1_ep: endpoint {
> > -                remote-endpoint = <&adv7611_ep>;
> > -                bus-width = <16>;
> > -
> > -                /*
> > -                 * If hsync-active/vsync-active are missing,
> > -                 * embedded BT.656 sync is used.
> > -                 */
> > -                 hsync-active = <0>; /* Active low */
> > -                 vsync-active = <0>; /* Active low */
> > -                 pclk-sample = <1>;  /* Rising */
> > +        ports {
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +
> > +            port@0 {
> > +                reg = <0>;
> > +                /* Parallel bus endpoint */
> > +                csi1_ep: endpoint {
> > +                    remote-endpoint = <&adv7611_ep>;
> > +                    bus-width = <16>;
> > +
> > +                    /*
> > +                     * If hsync-active/vsync-active are missing,
> > +                     * embedded BT.656 sync is used.
> > +                     */
> > +                     hsync-active = <0>; /* Active low */
> > +                     vsync-active = <0>; /* Active low */
> > +                     pclk-sample = <1>;  /* Rising */
> > +                };
> >              };
> >          };
> >      };
> 
> I'd keep the original example and add one with the CSI bridge

Understood, will do.

Thanks,

Paul

-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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