linux-kernel - Re: [PATCH 1/3] media: dt-bindings: nxp,imx8-isi: Add i.MX95 ISI compatible string

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Message-ID: <20251026220438.GG13023@pendragon.ideasonboard.com>
Date: Mon, 27 Oct 2025 00:04:38 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Frank Li <Frank.li@....com>
Cc: Guoniu Zhou <guoniu.zhou@....nxp.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, linux-media@...r.kernel.org,
	devicetree@...r.kernel.org, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Guoniu Zhou <guoniu.zhou@....com>
Subject: Re: [PATCH 1/3] media: dt-bindings: nxp,imx8-isi: Add i.MX95 ISI
 compatible string

On Fri, Oct 24, 2025 at 09:34:14AM -0400, Frank Li wrote:
> On Fri, Oct 24, 2025 at 05:46:52PM +0800, Guoniu Zhou wrote:
> > From: Guoniu Zhou <guoniu.zhou@....com>
> >
> > The ISI module on i.MX95 supports up to eight channels and four link
> > sources to obtain the image data for processing in its pipelines. It
> > can process up to eight image sources at the same time.
> >
> > Signed-off-by: Guoniu Zhou <guoniu.zhou@....com>
> > ---
> >  .../devicetree/bindings/media/nxp,imx8-isi.yaml    | 26 +++++++++++++++++++++-
> >  1 file changed, 25 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/devicetree/bindings/media/nxp,imx8-isi.yaml b/Documentation/devicetree/bindings/media/nxp,imx8-isi.yaml
> > index f43b91984f0152fbbcf80db3b3bbad7e8ad6c11e..eaab98ecf343a2cd3620f7469c016c3955d37406 100644
> > --- a/Documentation/devicetree/bindings/media/nxp,imx8-isi.yaml
> > +++ b/Documentation/devicetree/bindings/media/nxp,imx8-isi.yaml
> > @@ -23,6 +23,7 @@ properties:
> >        - fsl,imx8mp-isi
> >        - fsl,imx8ulp-isi
> >        - fsl,imx93-isi
> > +      - fsl,imx95-isi
> >
> >    reg:
> >      maxItems: 1
> > @@ -49,7 +50,7 @@ properties:
> >    interrupts:
> >      description: Processing pipeline interrupts, one per pipeline
> >      minItems: 1
> > -    maxItems: 2
> > +    maxItems: 8
> >
> >    power-domains:
> >      maxItems: 1
> > @@ -109,6 +110,29 @@ allOf:
> >              - port@0
> >              - port@1
> >
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: fsl,imx95-isi
> > +    then:
> > +      properties:
> > +        interrupts:
> > +          maxItems: 8
> 
> should minItems: 8 because you already limit maxItems at top;

As far as I understand, when no "items" are specified, minItems defaults
to 1, and maxItems defaults to minItems (if specified) or 0 (if minItems
is not specified). This is implemented in dtschema/lib.py of
https://github.com/devicetree-org/dt-schema.git.

Then, in dtschema/fixups.py, if only one of minItems or maxItems is
specified, the other one is set to the same value. I believe relying on
this is frowned upon by the DT maintainers.

We could specify minItems only here, as the top-level constraint will
ensure we don't go over 8. That's not very future-proof though, so I
think specifying both minItems and maxItems would be best. Confirmation
from a DT maintainer would be appreciated.

The fsl,imx8mp-isi block above should then be fixed. It currently only
has maxItems set, minItems should be set to 2 as well.

> > +        ports:
> > +          properties:
> > +            port@0:
> > +              description: Pixel Link Slave 0
> > +            port@1:
> > +              description: Pixel Link Slave 1
> > +            port@2:
> > +              description: MIPI CSI-2 RX 0
> > +            port@3:
> > +              description: MIPI CSI-2 RX 1
> > +          required:
> > +            - port@2
> > +            - port@3
> > +
> 
>      else
>        properties:
>          interrupts:
>            maxItem: 2
> 
> to keep the same restriction for existed compatible string.

We already specify the number of interrupts in two separate conditional
blocks above, with any else statement (for all but fsl,imx8mp-isi first,
and then for fsl,imx8mp-isi). Both specify maxItems, so I think we're
fine.

> >  additionalProperties: false
> >
> >  examples:

-- 
Regards,

Laurent Pinchart