linux-kernel - Re: [RFC v3] dt-binding: media: document ON Semi AR0521 sensor bindings

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Message-ID: <20210727105830.GH3@valkosipuli.retiisi.eu>
Date:   Tue, 27 Jul 2021 13:58:30 +0300
From:   Sakari Ailus <sakari.ailus@....fi>
To:     Krzysztof Hałasa <khalasa@...p.pl>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        devicetree@...r.kernel.org,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC v3] dt-binding: media: document ON Semi AR0521 sensor
 bindings

Hi Krzysztof,

On Tue, Jul 27, 2021 at 12:36:20PM +0200, Krzysztof Hałasa wrote:
> Hi Laurent,
> 
> Laurent Pinchart <laurent.pinchart@...asonboard.com> writes:
> 
> >> +        properties:
> >> +          data-lanes:
> >> +            anyOf:
> >> +              - items:
> >> +                  - const: 1
> >> +              - items:
> >> +                  - const: 1
> >> +                  - const: 2
> >> +              - items:
> >> +                  - const: 1
> >> +                  - const: 2
> >> +                  - const: 3
> >> +                  - const: 4
> >
> > As the sensor also supports an HiSPi output, I would add the bus-type
> > property:
> >
> >           data-lanes:
> > 	    const: 4
> 
> Is there any example of this? I'm not sure how should it it look like.
> Something like the following?
> 
>         properties:
>          data-lanes:
>             anyOf:
>               - items:
>                   - const: 1
>               - items:
>                   - const: 1
>                   - const: 2
>               - items:
>                   - const: 1
>                   - const: 2
>                   - const: 3
>                   - const: 4
>           bus-type:
>             data-lanes:
>               const: 4

I think Laurent meant:

	    bus-type:
	      const: 4

This way the bindings can be later amended with HiSPi support without
relying on defaults. Albeit the other busses in practice almost never end
up being used even if supported, apart from the standard BT.601, BT.656 and
CSI-2.

Either way is fine IMO.

> 
> And... HiSPi would need additional code in the driver. And preferably
> some testing. I think I'd prefer to have DT and the driver staying in
> some sort of sync. Also, I'm uncertain about the syntax and the meaning
> of such, apparently redundant, construct. Nor about its relation to
> HiSPi. An example would be welcome.

No need to add support for the driver.

-- 
Sakari Ailus