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

Paul Kocialkowski
2022-02-11T16:10:35Z

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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@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?

Thanks,

Paul

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

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

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