Re: [PATCH v5 2/3] media: dt-bindings: alvium: add document YAML binding

[Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>]

Hi Tommaso,

On Thu, Jun 08, 2023 at 10:31:15AM +0200, Tommaso Merciai wrote:
> Add documentation of device tree in YAML schema for the ALVIUM
> Camera from Allied Vision Inc.
> 
> References:
>  - https://www.alliedvision.com/en/products/embedded-vision-solutions
> 
> Signed-off-by: Tommaso Merciai <tomm.merciai@xxxxxxxxx>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
> Changes since v1:
>  - Fixed build error as suggested by RHerring bot
> 
> Changes since v2:
>  - Fixed License as suggested by KKozlowski/CDooley
>  - Removed rotation property as suggested by CDooley/LPinchart
>  - Fixed example node name as suggested by CDooley
>  - Fixed title as suggested by LPinchart
>  - Fixed compatible name as suggested by LPinchart
>  - Removed clock as suggested by LPinchart
>  - Removed gpios not as suggested by LPinchart
>  - Renamed property name streamon-delay into alliedvision,lp2hs-delay-us
>  - Fixed vendor prefix, unit append as suggested by KKozlowski
>  - Fixed data-lanes
>  - Fixed blank space + example indentation (from 6 -> 4 space) as suggested by KKozlowski
>  - Dropped status into example  as suggested by KKozlowski
>  - Added vcc-ext-in supply as suggested by LPinchart
>  - Dropped pinctrl into example as suggested by LPinchart
> 
> Changes since v3:
>  - Fixed vcc-ext-in-supply description as suggested by LPinchart
>  - Fixed alliedvision,lp2hs-delay-us description as suggested by LPinchart
>  - Added maximum to alliedvision,lp2hs-delay-us as suggested by LPinchart
>  - Collected Reviewed-by tag from LPinchart
> 
> Changes since v4:
>  - Fixed id as reported by RHerring bot and LPinchart
>  - Add minimum into alliedvision,lp2hs-delay-us as suggested by CDooley
>  - Tested using make dt_binding_check DT_SCHEMA_FILES=alliedvision,alvium-csi2.yaml
> 
>  .../media/i2c/alliedvision,alvium-csi2.yaml   | 97 +++++++++++++++++++
>  1 file changed, 97 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/i2c/alliedvision,alvium-csi2.yaml
> 
> diff --git a/Documentation/devicetree/bindings/media/i2c/alliedvision,alvium-csi2.yaml b/Documentation/devicetree/bindings/media/i2c/alliedvision,alvium-csi2.yaml
> new file mode 100644
> index 000000000000..c771e5039641
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/i2c/alliedvision,alvium-csi2.yaml
> @@ -0,0 +1,97 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/media/i2c/alliedvision,alvium-csi2.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Allied Vision Alvium Camera
> +
> +maintainers:
> +  - Tommaso Merciai <tomm.merciai@xxxxxxxxx>
> +  - Martin Hecht <martin.hecht@xxxxxxxx>
> +
> +allOf:
> +  - $ref: /schemas/media/video-interface-devices.yaml#
> +
> +properties:
> +  compatible:
> +    const: alliedvision,alvium-csi2
> +
> +  reg:
> +    maxItems: 1
> +
> +  vcc-ext-in-supply:
> +    description: |
> +      The regulator that supplies power to the VCC_EXT_IN pins.
> +
> +  alliedvision,lp2hs-delay-us:
> +    minimum: 1
> +    maximum: 150000
> +    description: |
> +      Low power to high speed delay time.
> +
> +      If the value is larger than 0, the camera forces a reset of all
> +      D-PHY lanes for the duration specified by this property. All lanes
> +      will transition to the low-power state and back to the high-speed
> +      state after the delay. Otherwise the lanes will transition to and
> +      remain in the high-speed state immediately after power on.
> +
> +      This is meant to help CSI-2 receivers synchronizing their D-PHY
> +      RX.

Why do you need this? D-PHY TX is obviously controlled by the driver.
Explicit control of PHY initialisation is of course best option when
combined with some receivers, done via driver's pre_streamon and s_stream
callbacks. Can't your hardware do that?

> +
> +  port:
> +    description: Digital Output Port
> +    $ref: /schemas/graph.yaml#/$defs/port-base
> +    additionalProperties: false
> +
> +    properties:
> +      endpoint:
> +        $ref: /schemas/media/video-interfaces.yaml#
> +        unevaluatedProperties: false
> +
> +        properties:
> +          link-frequencies: true
> +
> +          data-lanes:
> +            minItems: 1
> +            items:
> +              - const: 1
> +              - const: 2
> +              - const: 3
> +              - const: 4
> +
> +        required:
> +          - data-lanes
> +          - link-frequencies
> +
> +required:
> +  - compatible
> +  - reg
> +  - vcc-ext-in-supply
> +  - port
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        alvium: camera@3c {
> +            compatible = "alliedvision,alvium-csi2";
> +            reg = <0x3c>;
> +            vcc-ext-in-supply = <&reg_vcc_ext_in>;
> +            alliedvision,lp2hs-delay-us = <20>;
> +
> +            port {
> +                alvium_out: endpoint {
> +                    remote-endpoint = <&mipi_csi_0_in>;
> +                    data-lanes = <1 2 3 4>;
> +                    link-frequencies = /bits/ 64 <681250000>;
> +                };
> +            };
> +        };
> +    };
> +
> +...

-- 
Regards,

Sakari Ailus