linux-kernel - RE: [PATCH v5 1/6] dt-bindings: media: platform: visconti: Add Toshiba Visconti Video Input Interface bindings

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Message-ID: <TYAPR01MB6201BCC60149D17F59AD870E92D39@TYAPR01MB6201.jpnprd01.prod.outlook.com>
Date:   Mon, 30 Jan 2023 09:06:25 +0000
From:   <yuji2.ishikawa@...hiba.co.jp>
To:     <laurent.pinchart@...asonboard.com>,
        <krzysztof.kozlowski@...aro.org>
CC:     <hverkuil@...all.nl>, <mchehab@...nel.org>,
        <nobuhiro1.iwamatsu@...hiba.co.jp>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <rafael.j.wysocki@...el.com>,
        <broonie@...nel.org>, <linux-media@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>
Subject: RE: [PATCH v5 1/6] dt-bindings: media: platform: visconti: Add
 Toshiba Visconti Video Input Interface bindings



> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Sent: Monday, January 23, 2023 4:26 AM
> To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> Cc: ishikawa yuji(石川 悠司 ○ＲＤＣ□ＡＩＴＣ○ＥＡ開)
> <yuji2.ishikawa@...hiba.co.jp>; Hans Verkuil <hverkuil@...all.nl>; Mauro
> Carvalho Chehab <mchehab@...nel.org>; iwamatsu nobuhiro(岩松 信洋 □Ｓ
> ＷＣ◯ＡＣＴ) <nobuhiro1.iwamatsu@...hiba.co.jp>; Rob Herring
> <robh+dt@...nel.org>; Krzysztof Kozlowski
> <krzysztof.kozlowski+dt@...aro.org>; Rafael J . Wysocki
> <rafael.j.wysocki@...el.com>; Mark Brown <broonie@...nel.org>;
> linux-media@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
> linux-kernel@...r.kernel.org; devicetree@...r.kernel.org
> Subject: Re: [PATCH v5 1/6] dt-bindings: media: platform: visconti: Add Toshiba
> Visconti Video Input Interface bindings
> 
> Hi Krzysztof,
> 
> On Tue, Jan 17, 2023 at 06:01:27PM +0100, Krzysztof Kozlowski wrote:
> > On 17/01/2023 16:58, Laurent Pinchart wrote:
> > > On Tue, Jan 17, 2023 at 04:42:51PM +0100, Krzysztof Kozlowski wrote:
> > >> On 17/01/2023 16:26, Laurent Pinchart wrote:
> > >>>
> > >>>> +
> > >>>> +          clock-lanes:
> > >>>> +            description: VIIF supports 1 clock line
> > >>>
> > >>> s/line/lane/

Sorry for a late reply.
I'll fix the description.

> > >>>
> > >>>> +            const: 0
> > >>>
> > >>> I would also add
> > >>>
> > >>>           clock-noncontinuous: true
> > >>>           link-frequencies: true
> > >>>
> > >>> to indicate that the above two properties are used by this device.
> > >>
> > >> No, these are coming from other schema and there is never need to
> > >> mention some property to indicate it is more used than other case.
> > >> None of the bindings are created such way, so this should not be
> exception.
> > >
> > > There are some bindings that do so, but that may not be a good
> > > enough reason, as there's a chance I wrote those myself :-)
> > >
> > > I would have sworn that at some point in the past the schema
> > > wouldn't have validated the example with this omitted. I'm not sure
> > > if something changed or if I got this wrong.
> >
> > You probably think about case when using additionalProperties:false,
> > where one has to explicitly list all valid properties. But not for
> > unevaluatedProperties:false.
> 
> Possibly, yes.
> 
> > > video-interfaces.yaml defines lots of properties applicable to
> > > endpoints. For a given device, those properties should be required
> >
> > required:
> >  - foo
> >
> > > (easy, that's defined in the bindings), optional,
> >
> > by default (with unevaluatedProperties:false) or explicitly mention
> > "foo: true (with additionalProperties:false)
> >
> > >  or forbidden. How do
> >
> > foo: false (with unevaluatedProperties:false) or by default (with
> > additionalProperties:false)
> 
> I think we should default to the latter. video-interfaces.yaml contains lots of
> properties endpoint properties, most bindings will use less than half of them, so
> having to explicitly list all the ones that are not used with "foo: false" would be
> quite inconvenient. Furthermore, I expect more properties to be added to
> video-interfaces.yaml over time, and those shouldn't be accepted by default in
> existing bindings.
> 

I caught up with this discussion after some exercise on JSON schema validator.
I'll remove "unevaluatedProperties: false" at the "endpoint" and add "aditionalProperties: false" instead.
Furthermore, I'll explicitly declare required properties (required: ["foo"]) and optional properties (properties: {foo: true}) for Visconti.
Is this correct understanding?
Are these changes also applied to "port", which is the parent node of the "endpoint" ?

> > > we differentiate between the latter two cases ?
> 
> --
> Regards,
> 
> Laurent Pinchart

Regards,
Yuji Ishikawa