RE: [PATCH v12 2/8] dt-bindings: media: platform: visconti: Add Toshiba Visconti Video Input Interface

[<yuji2.ishikawa@toshiba.co.jp>]

Hello Laurent.

Thank you for your review comments.

> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Sent: Thursday, January 2, 2025 6:56 PM
> To: ishikawa yuji(石川 悠司 ○ＲＤＣ□ＡＩＴＣ○ＥＡ開)
> <yuji2.ishikawa@toshiba.co.jp>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>; Rob Herring
> <robh@kernel.org>; Krzysztof Kozlowski <krzk+dt@kernel.org>; Conor Dooley
> <conor+dt@kernel.org>; Sakari Ailus <sakari.ailus@linux.intel.com>; Hans
> Verkuil <hverkuil-cisco@xs4all.nl>; iwamatsu nobuhiro(岩松 信洋 ○ＤＩＴＣ
> □ＤＩＴ○ＯＳＴ) <nobuhiro1.iwamatsu@toshiba.co.jp>;
> linux-media@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-arm-kernel@lists.infradead.org; devicetree@vger.kernel.org
> Subject: Re: [PATCH v12 2/8] dt-bindings: media: platform: visconti: Add
> Toshiba Visconti Video Input Interface
> 
> Hi Ishikawa-san,
> 
> Thank you for the patch.
> 
> On Mon, Nov 25, 2024 at 06:21:40PM +0900, Yuji Ishikawa wrote:
> > Adds the Device Tree binding documentation that allows to describe the
> > Video Input Interface found in Toshiba Visconti SoCs.
> >
> > Signed-off-by: Yuji Ishikawa <yuji2.ishikawa@toshiba.co.jp>
> > Reviewed-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
> > ---
> > Changelog v2:
> > - no change
> >
> > Changelog v3:
> > - no change
> >
> > Changelog v4:
> > - fix style problems at the v3 patch
> > - remove "index" member
> > - update example
> >
> > Changelog v5:
> > - no change
> >
> > Changelog v6:
> > - add register definition of BUS-IF and MPU
> >
> > Changelog v7:
> > - remove trailing "bindings" from commit header message
> > - remove trailing "Device Tree Bindings" from title
> > - fix text wrapping of description
> > - change compatible to visconti5-viif
> > - explicitly define allowed properties for port::endpoint
> >
> > Changelog v8:
> > - Suggestion from Krzysztof Kozlowski
> >   - rename bindings description file
> >   - use block style array instead of inline style
> >   - remove clock-lane (as it is fixed at position 0)
> >   - update sample node's name
> >   - use lowercase hex for literals
> > - Suggestion from Laurent Pinchart
> >   - update description message port::description
> >   - remove port::endpoint::bus-type as it is fixed to <4>
> >   - remove port::endpoint::clock-lanes from example
> >   - add port::endpoint::data-lanes to required parameters list
> >   - fix sequence of data-lanes: <1 2 3 4> because current driver does not
> support data reordering
> >   - update port::endpoint::data-lanes::description
> >   - remove redundant type definition for port::endpoint::data-lanes
> >
> > Changelog v9:
> > - place "required" after "properties"
> > - dictionary ordering of properties
> >
> > Changelog v10:
> > - no change
> >
> > Changelog v11:
> > - no change
> >
> > Changelog v12:
> > - remove property "clock-noncontinuous" as VIIF switches both modes
> > automatically
> > - remove property "link-frequencies" as VIIF does not use the
> > information
> > - remove reg[2] and interrupts[3] which are used for CSI2RX driver
> > - update example to refer csi2rx for remote-endpoint
> >
> >  .../media/toshiba,visconti5-viif.yaml         | 95
> +++++++++++++++++++
> >  1 file changed, 95 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/media/toshiba,visconti5-viif.yaml
> >
> > diff --git
> > a/Documentation/devicetree/bindings/media/toshiba,visconti5-viif.yaml
> > b/Documentation/devicetree/bindings/media/toshiba,visconti5-viif.yaml
> > new file mode 100644
> > index 000000000000..ef0452a47e98
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/media/toshiba,visconti5-viif.y
> > +++ aml
> > @@ -0,0 +1,95 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) %YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/media/toshiba,visconti5-viif.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Toshiba Visconti5 SoC Video Input Interface
> > +
> > +maintainers:
> > +  - Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
> > +
> > +description: |-
> > +  Toshiba Visconti5 SoC Video Input Interface (VIIF) receives
> > +videostream
> > +  from MIPI CSI-2 receiver device, processes the stream with image
> > +signal
> > +  processors (L1ISP, L2ISP), then stores pictures to main memory.
> > +
> > +properties:
> > +  compatible:
> > +    const: toshiba,visconti5-viif
> > +
> > +  reg:
> > +    items:
> > +      - description: Registers for capture control
> > +      - description: Registers for bus interface unit control
> > +      - description: Registers for Memory Protection Unit
> 
> I'm a bit surprised by the lack of clocks.
> 

The VIIF HW requires clock input. However, since the clock controller driver is still in development and no corresponding clock source is available,
I did not describe the VIIF clock in the device tree and the binding.
I understand that a clock should be defined in the binding.
For the next patch, I'll add a clock definition to the binding.

> > +
> > +  interrupts:
> > +    items:
> > +      - description: Sync Interrupt
> > +      - description: Status (Error) Interrupt
> > +      - description: L1ISP Interrupt
> > +
> > +  port:
> > +    $ref: /schemas/graph.yaml#/$defs/port-base
> > +    unevaluatedProperties: false
> > +    description: CSI-2 input port, with a single endpoint connected to the
> CSI-2 transmitter.
> > +
> > +    properties:
> > +      endpoint:
> > +        $ref: video-interfaces.yaml#
> > +        additionalProperties: false
> > +
> > +        properties:
> > +          data-lanes:
> > +            description: VIIF supports 1, 2, 3 or 4 data lanes
> > +            minItems: 1
> > +            items:
> > +              - const: 1
> > +              - const: 2
> > +              - const: 3
> > +              - const: 4
> 
> Now that the CSI-2 receiver is modeled as a separate DT node, I don't think
> data-lanes is applicable anymore. The interface between the CSI-2 receiver
> and the VIIF isn't a CSI-2 bus.
>
> I think you can simplify the bindings by switching from port-base to port, as you
> don't need to specify additional properties for the
> endpoint:
> 
>   port:
>     $ref: /schemas/graph.yaml#/$defs/port
>     description:
>       CSI-2 input port, with a single endpoint connected to the CSI-2
>       transmitter.
> 
> Please test this though (by running the DT bindings checks).
>

I'll remove CSI-2 specific descriptions.
Also I'll use a reference to port.

> > +
> > +          remote-endpoint: true
> > +
> > +        required:
> > +          - data-lanes
> > +          - remote-endpoint
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - interrupts
> > +  - port
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> > +    #include <dt-bindings/interrupt-controller/irq.h>
> > +
> > +    soc {
> > +        #address-cells = <2>;
> > +        #size-cells = <2>;
> > +
> > +        video@1c000000 {
> > +            compatible = "toshiba,visconti5-viif";
> > +            reg = <0 0x1c000000 0 0x6000>,
> > +                  <0 0x1c00e000 0 0x1000>,
> > +                  <0 0x2417a000 0 0x1000>;
> > +            interrupts = <GIC_SPI 64 IRQ_TYPE_LEVEL_HIGH>,
> > +                         <GIC_SPI 67 IRQ_TYPE_LEVEL_HIGH>,
> > +                         <GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH>;
> > +
> > +            port {
> > +                #address-cells = <1>;
> > +                #size-cells = <0>;
> > +
> > +                csi_in0: endpoint {
> > +                    data-lanes = <1 2>;
> > +                    remote-endpoint = <&csi2rx_out0>;
> > +                };
> > +            };
> > +        };
> > +    };
> 
> --
> Regards,
> 
> Laurent Pinchart

Regards,
Yuji Ishikawa