Re: [PATCH v2 07/66] dt-bindings: media: sun6i-a31-csi: Add MIPI CSI-2 input port

[Paul Kocialkowski]

Hi Laurent,

Thanks for the review!

On Mon 07 Feb 22, 18:03, Laurent Pinchart wrote:
> Hi Paul,
> 
> Thank you for the patch.
> 
> On Sat, Feb 05, 2022 at 07:53:30PM +0100, 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.
> 
> Is it that only one of the two is present, or only one of the two is
> connected ? In the latter case I'd make both ports required, but with
> only one of them connected.

There are situations where the actual pins for parallel (port@0) are missing
and the controller is dedicated to its mipi csi-2 bridge (port@1), cases where
the two are present and cases where the mipi csi-2 bridge doesn't exist.
So all in all it's really legit that only one port may be defined.

> > 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@xxxxxxxxxxx>
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> > Acked-by: Maxime Ripard <mripard@xxxxxxxxxx>
> > ---
> >  .../media/allwinner,sun6i-a31-csi.yaml        | 60 +++++++++++++++----
> >  1 file changed, 47 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..3cc61866ea89 100644
> > --- a/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-csi.yaml
> > +++ b/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-csi.yaml
> > @@ -61,6 +61,34 @@ properties:
> >  
> >      additionalProperties: false
> >  
> > +  ports:
> > +    $ref: /schemas/graph.yaml#/properties/ports
> > +
> > +    properties:
> > +      port@0:
> > +        $ref: "#/properties/port"
> > +        unevaluatedProperties: false
> > +
> > +      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
> > +
> > +    anyOf:
> > +      - required:
> > +        - port@0
> > +      - required:
> > +        - port@1
> > +
> >  required:
> >    - compatible
> >    - reg
> 
> Shouldn't you specify that either port or ports is required, but not
> both ? I'd also add a comment in the port node to tell it's deprecated,
> and that ports should be used instead.

Yes I agree on both points. I guess that should be a:

oneOf:
  - required:
    - ports
  - required:
    - port

(but feel free to correct me).

> > @@ -89,19 +117,25 @@ 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 */
> 
> Wrong indentation.

The double-space before /* Rising */ or something with the heading indent?

Thanks,

Paul

> > +                };
> >              };
> >          };
> >      };
> 
> -- 
> Regards,
> 
> Laurent Pinchart

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

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