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Date: Fri, 12 Apr 2024 11:10:32 +0000
From: Sakari Ailus <sakari.ailus@iki.fi>
To: Julien Massot <julien.massot@collabora.com>
Cc: linux-media@vger.kernel.org, devicetree@vger.kernel.org,
	kernel@collabora.com, linux-kernel@vger.kernel.org,
	mchehab@kernel.org, robh+dt@kernel.org,
	krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org
Subject: Re: [PATCH v6 1/4] dt-bindings: media: add Maxim MAX96717 GMSL2
 Serializer
Message-ID: <ZhkWqEAN4RozmPlT@valkosipuli.retiisi.eu>
References: <20240325131634.165361-1-julien.massot@collabora.com>
 <20240325131634.165361-2-julien.massot@collabora.com>
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In-Reply-To: <20240325131634.165361-2-julien.massot@collabora.com>

Hi Julien,

On Mon, Mar 25, 2024 at 02:16:31PM +0100, Julien Massot wrote:
> Add DT bindings for Maxim MAX96717 GMSL2 Serializer.
> 
> Signed-off-by: Julien Massot <julien.massot@collabora.com>
> ---
> Change since v5:
>  - Reverse the fallback MAX96717 can fallback to MAX96717F
>  - Use const instead of enum for MAX96717F compatible
>  
> Change since v4:
>  - Add compatible for MAX96717 and use it as a fallback for MAX96717F
>  - Remove extra '|' for decriptions
>  - Reference 'i2c-gate' instead of 'i2c-controller'
> 
> Change since v3:
>  - Renamed file to maxim,max96717.yaml dropped the 'f' suffix
>  - Added lane-polarities and bus type properties to the CSI endpoint
> 
> Change since v2:
>  - remove reg description
>  - add data lanes min/maxItems
>  - Use generic node name 
> ---
>  .../bindings/media/i2c/maxim,max96717.yaml    | 164 ++++++++++++++++++
>  1 file changed, 164 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/i2c/maxim,max96717.yaml
> 
> diff --git a/Documentation/devicetree/bindings/media/i2c/maxim,max96717.yaml b/Documentation/devicetree/bindings/media/i2c/maxim,max96717.yaml
> new file mode 100644
> index 000000000000..ac8bf11a6fa5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/i2c/maxim,max96717.yaml
> @@ -0,0 +1,164 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright (C) 2024 Collabora Ltd.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/media/i2c/maxim,max96717.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MAX96717 CSI-2 to GMSL2 Serializer
> +
> +maintainers:
> +  - Julien Massot <julien.massot@collabora.com>
> +
> +description:
> +  The MAX96717 serializer converts MIPI CSI-2 D-PHY or C-PHY formatted input
> +  into GMSL2 serial outputs. The device allows the GMSL2 link to
> +  simultaneously transmit bidirectional control-channel data while forward
> +  video transmissions are in progress. The MAX96717 can connect to one
> +  remotely located deserializer using industry-standard coax or STP
> +  interconnects. The device cans operate in pixel or tunnel mode. In pixel mode
> +  the MAX96717 can select the MIPI datatype, while the tunnel mode forward all the MIPI
> +  data received by the serializer.
> +  The MAX96717 supports Reference Over Reverse (channel),
> +  to generate a clock output for the sensor from the GMSL reverse channel.
> +
> +  The GMSL2 serial link operates at a fixed rate of 3Gbps or 6Gbps in the
> +  forward direction and 187.5Mbps in the reverse direction.
> +  MAX96717F only supports a fixed rate of 3Gbps in the forward direction.
> +
> +properties:
> +  compatible:
> +    oneOf:
> +      - const: maxim,max96717f
> +      - items:
> +          - enum:
> +              - maxim,max96717
> +          - const: maxim,max96717f
> +
> +  '#gpio-cells':
> +    const: 2
> +    description:
> +      First cell is the GPIO pin number, second cell is the flags. The GPIO pin
> +      number must be in range of [0, 10].
> +
> +  gpio-controller: true
> +
> +  '#clock-cells':
> +    const: 0
> +
> +  reg:
> +    maxItems: 1
> +
> +  ports:
> +    $ref: /schemas/graph.yaml#/properties/ports
> +
> +    properties:
> +      port@0:
> +        $ref: /schemas/graph.yaml#/$defs/port-base
> +        unevaluatedProperties: false
> +        description: CSI-2 Input port
> +
> +        properties:
> +          endpoint:
> +            $ref: /schemas/media/video-interfaces.yaml#
> +            unevaluatedProperties: false
> +
> +            properties:
> +              data-lanes:
> +                minItems: 1
> +                maxItems: 4
> +
> +              lane-polarities:
> +                minItems: 1
> +                maxItems: 5
> +
> +              bus-type:
> +                enum:
> +                  - 1 # MEDIA_BUS_TYPE_CSI2_CPHY
> +                  - 4 # MEDIA_BUS_TYPE_CSI2_DPHY

Now that you have C-PHY here, does the hardware support data line order
mapping? Just wondering. The bindings can be added without that and support
added later on---that's what the video-interfaces.yaml is currently
missing.

lane-polarities is only valid for D-PHY. What about the data-lanes, the
maximum is probably different for C-PHY?

> +
> +            required:
> +              - data-lanes
> +              - bus-type
> +
> +      port@1:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        unevaluatedProperties: false
> +        description: GMSL Output port
> +
> +    required:
> +      - port@1
> +
> +  i2c-gate:
> +    $ref: /schemas/i2c/i2c-gate.yaml
> +    unevaluatedProperties: false
> +    description:
> +      The MAX96717 will forward the I2C requests from the
> +      incoming GMSL2 link. Therefore, it supports an i2c-gate
> +      subnode to configure a sensor.
> +
> +required:
> +  - compatible
> +  - reg
> +  - ports
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/media/video-interfaces.h>
> +
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +        serializer: serializer@40 {
> +            compatible = "maxim,max96717f";
> +            reg = <0x40>;
> +            gpio-controller;
> +            #gpio-cells = <2>;
> +            #clock-cells = <0>;
> +
> +            ports {
> +                #address-cells = <1>;
> +                #size-cells = <0>;
> +
> +                port@0 {
> +                    reg = <0>;
> +                    max96717f_csi_in: endpoint {
> +                        bus-type = <MEDIA_BUS_TYPE_CSI2_DPHY>;
> +                        data-lanes = <1 2 3 4>;
> +                        remote-endpoint = <&sensor_out>;
> +                    };
> +                };
> +
> +                port@1 {
> +                    reg = <1>;
> +                    max96917f_gmsl_out: endpoint {
> +                        remote-endpoint = <&deser_gmsl_in>;
> +                    };
> +                };
> +            };
> +
> +            i2c-gate {
> +                #address-cells = <1>;
> +                #size-cells = <0>;
> +                sensor@10 {
> +                    compatible = "st,st-vgxy61";
> +                    reg = <0x10>;
> +                    reset-gpios = <&serializer 0 GPIO_ACTIVE_LOW>;
> +                    clocks = <&serializer>;
> +                    VCORE-supply = <&v1v2>;
> +                    VDDIO-supply = <&v1v8>;
> +                    VANA-supply = <&v2v8>;
> +                    port {
> +                        sensor_out: endpoint {
> +                            data-lanes = <1 2 3 4>;
> +                            remote-endpoint = <&max96717f_csi_in>;
> +                        };
> +                    };
> +                };
> +            };
> +        };
> +    };
> +...

-- 
Regards,

Sakari Ailus