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

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

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Hi,

On Fri 11 Feb 22, 22:56, Laurent Pinchart wrote:
> On Fri, Feb 11, 2022 at 05:10:06PM +0100, Paul Kocialkowski wrote:
> > 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.
> 
> The port could still exist internally in the IP core though. Of course
> that's hard to tell.

Yes that's true, the bit to switch input to mipi csi-2 is there in all cases
but I don't think it makes sense to expose the port in situations where
no controller is attached.

> > > > 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        | 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?
> 
> The heading has one extra space for all three lines, they should be
> aligned to the / of /*, not to the *.

Oh that's true, good catch thanks!

Paul

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

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

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