linux-kernel - Re: [PATCH v4 2/5] dt-bindings: media: add mediatek ISP3.0 camsv

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Message-ID: <20240112074141.GA21256@pendragon.ideasonboard.com>
Date: Fri, 12 Jan 2024 09:41:41 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Julien Stephan <jstephan@...libre.com>,
	Phi-bang Nguyen <pnguyen@...libre.com>,
	Andy Hsieh <andy.hsieh@...iatek.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
	Florian Sylvestre <fsylvestre@...libre.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-mediatek@...ts.infradead.org, linux-media@...r.kernel.org,
	Louis Kuo <louis.kuo@...iatek.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Paul Elder <paul.elder@...asonboard.com>,
	Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v4 2/5] dt-bindings: media: add mediatek ISP3.0 camsv

On Fri, Jan 12, 2024 at 08:34:45AM +0100, Krzysztof Kozlowski wrote:
> On 10/01/2024 15:14, Julien Stephan wrote:
> > From: Phi-bang Nguyen <pnguyen@...libre.com>
> > 
> > This adds the bindings, for the ISP3.0 camsv module embedded in
> > some Mediatek SoC, such as the mt8365
> > 
> > Signed-off-by: Phi-bang Nguyen <pnguyen@...libre.com>
> > Signed-off-by: Julien Stephan <jstephan@...libre.com>
> > Link: https://lore.kernel.org/r/20230807094940.329165-4-jstephan@baylibre.com
> > ---
> >  .../bindings/media/mediatek,mt8365-camsv.yaml | 109 ++++++++++++++++++
> >  MAINTAINERS                                   |   1 +
> >  2 files changed, 110 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/media/mediatek,mt8365-camsv.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/media/mediatek,mt8365-camsv.yaml b/Documentation/devicetree/bindings/media/mediatek,mt8365-camsv.yaml
> > new file mode 100644
> > index 000000000000..097b1ab6bc72
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/media/mediatek,mt8365-camsv.yaml
> > @@ -0,0 +1,109 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +# Copyright (c) 2023 MediaTek, BayLibre
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/media/mediatek,mt8365-camsv.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: MediaTek CAMSV 3.0
> > +
> > +maintainers:
> > +  - Laurent Pinchart <laurent.pinchart@...asonboard.com>
> > +  - Julien Stephan <jstephan@...libre.com>
> > +  - Andy Hsieh <andy.hsieh@...iatek.com>
> > +
> > +description:
> > +  The CAMSV is a set of DMA engines connected to the SENINF CSI-2
> > +  receivers. The number of CAMSVs depend on the SoC model.
> 
> DMA should not go to media, but to dma

They're not generic DMA engines. The CAMSV is a video capture device
that includes a DMA engine, much like pretty much all the other video
capture devices.

> > +
> > +properties:
> > +  compatible:
> > +    const: mediatek,mt8365-camsv
> > +
> > +  reg:
> > +    items:
> > +      - description: camsv base
> > +      - description: img0 base
> > +      - description: tg base
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +
> > +  power-domains:
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    items:
> > +      - description: cam clock
> > +      - description: camtg clock
> > +      - description: camsv clock
> > +
> > +  clock-names:
> > +    items:
> > +      - const: cam
> > +      - const: camtg
> > +      - const: camsv
> > +
> > +  iommus:
> > +    maxItems: 1
> > +
> > +  ports:
> > +    $ref: /schemas/graph.yaml#/properties/ports
> > +
> > +    properties:
> > +      port@0:
> > +        $ref: /schemas/graph.yaml#/properties/port
> > +        description: connection point for camsv0
> 
> This explains me nothing. What type of connection point? How does it fit
> the pipeline going to the display?

The description seems wrong, it should state

        description: Connection to the SENINF output

or something similar.

> It seems you represented DMA as some other device to make your drivers
> easier... That's not how it works.
> 
> > +
> > +    required:
> > +      - port@0
> > +
> > +required:
> > +  - compatible
> > +  - interrupts
> > +  - clocks
> > +  - clock-names
> > +  - power-domains
> > +  - iommus
> > +  - ports
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> > +    #include <dt-bindings/interrupt-controller/irq.h>
> > +    #include <dt-bindings/clock/mediatek,mt8365-clk.h>
> > +    #include <dt-bindings/memory/mediatek,mt8365-larb-port.h>
> > +    #include <dt-bindings/power/mediatek,mt8365-power.h>
> > +
> > +    soc {
> > +        #address-cells = <2>;
> > +        #size-cells = <2>;
> > +
> > +        camsv1: camsv@...50000 {
> 
> Node names should be generic. See also an explanation and list of
> examples (not exhaustive) in DT specification:
> https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation

-- 
Regards,

Laurent Pinchart