Re: [PATCH v2 61/66] dt-bindings: media: Add Allwinner A31 ISP bindings documentation

Laurent Pinchart
2022-02-14T17:11:12Z

On Mon, Feb 14, 2022 at 05:28:50PM +0100, Paul Kocialkowski wrote:
> Hi,
>
> On Fri 11 Feb 22, 22:52, Laurent Pinchart wrote:
> > Hi Rob,
> >
> > On Fri, Feb 11, 2022 at 09:13:30AM -0600, Rob Herring wrote:
> > > On Mon, Feb 07, 2022 at 05:51:21PM +0200, Laurent Pinchart wrote:
> > > > On Sat, Feb 05, 2022 at 07:54:24PM +0100, Paul Kocialkowski wrote:
> > > > > This introduces YAML bindings documentation for the Allwinner A31 Image
> > > > > Signal Processor (ISP).
> > > > >
> > > > > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > > > > ---
> > > > > .../media/allwinner,sun6i-a31-isp.yaml | 117 ++++++++++++++++++
> > > > > 1 file changed, 117 insertions(+)
> > > > > create mode 100644 Documentation/devicetree/bindings/media/allwinner,sun6i-a31-isp.yaml
> > > > >
> > > > > diff --git a/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-isp.yaml b/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-isp.yaml
> > > > > new file mode 100644
> > > > > index 000000000000..2d87022c43ce
> > > > > --- /dev/null
> > > > > +++ b/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-isp.yaml
> > > > > @@ -0,0 +1,117 @@
> > > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > > > +%YAML 1.2
> > > > > +---
> > > > > +$id: http://devicetree.org/schemas/media/allwinner,sun6i-a31-isp.yaml#
> > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > > +
> > > > > +title: Allwinner A31 Image Signal Processor Driver (ISP) Device Tree Bindings
> > > > > +
> > > > > +maintainers:
> > > > > + - Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > > > > +
> > > > > +properties:
> > > > > + compatible:
> > > > > + enum:
> > > > > + - allwinner,sun6i-a31-isp
> > > > > + - allwinner,sun8i-v3s-isp
> > > > > +
> > > > > + reg:
> > > > > + maxItems: 1
> > > > > +
> > > > > + interrupts:
> > > > > + maxItems: 1
> > > > > +
> > > > > + clocks:
> > > > > + items:
> > > > > + - description: Bus Clock
> > > > > + - description: Module Clock
> > > > > + - description: DRAM Clock
> > > >
> > > > That's interesting, does the ISP have a dedicated DRAM ?
> > > >
> > > > > +
> > > > > + clock-names:
> > > > > + items:
> > > > > + - const: bus
> > > > > + - const: mod
> > > > > + - const: ram
> > > > > +
> > > > > + resets:
> > > > > + maxItems: 1
> > > > > +
> > > > > + ports:
> > > > > + $ref: /schemas/graph.yaml#/properties/ports
> > > > > +
> > > > > + properties:
> > > > > + port@0:
> > > > > + $ref: /schemas/graph.yaml#/$defs/port-base
> > > > > + description: CSI0 input port
> > > > > +
> > > > > + properties:
> > > > > + reg:
> > > > > + const: 0
> > > > > +
> > > > > + endpoint:
> > > > > + $ref: video-interfaces.yaml#
> > > > > + unevaluatedProperties: false
> > > >
> > > > If no other property than remote-endpoint are allowed, I'd write
> > > >
> > > > endpoint:
> > > > $ref: video-interfaces.yaml#
> > > > remote-endpoint: true
> > >
> > > You just mixed a node and a property...
> >
> > Yes, I meant
> >
> > endpoint:
> > $ref: video-interfaces.yaml#
> > properties:
> > remote-endpoint: true
> >
> > and actually add
> >
> > additionalProperties: false
> >
> > > 'remote-endpoint' is always allowed, so need to put it here and every
> > > other user. So 'unevaluatedProperties' is correct. But it would be good
> > > to define what properties from video-interfaces.yaml are used here.
> >
> > I've been looking at this recently. The usual pattern is to write
> >
> > endpoint:
> > $ref: video-interfaces.yaml#
> > unevaluatedProperties: false
> > properties:
> > hsync-polarity: true
> > vsync-polarity: true
> >
> > to express that the hsync-polarity and vsync-polarity properties are
> > used. However, this will still validate fine if, for instance,
> > data-lanes was specified in the device tree. Shouldn't we use
> > additionalProperties instead of unevaluatedProperties here ? If so,
> > specifying remote-endpoint: true seems needed.
>
> My understanding is that unevaluatedProperties well allow all properties
> defined in the included video-interfaces.yaml ref but reject others
> while additionalProperties will reject any unspecified local property,
> even if it is declared in the ref.
>
> In any case with the ISP maybe we don't even want to take the ref from
> video-interfaces.yaml since we are dealing with an internal fifo between
> two devices. Maybe it would be more appropriate to ref
> /schemas/graph.yaml#/$defs/endpoint-base, which already defines
> remote-endpoint too.
>
> What do you think?

Yes, if no additional property are needed, you can replace port-base
with port, it will simplify the bindings.

--
Regards,

Laurent Pinchart