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

[Tommaso Merciai <tomm.merciai@xxxxxxxxx>]

Hi Sakari,
Thanks for your feedback.

On Fri, Jun 09, 2023 at 08:35:20AM +0000, Sakari Ailus wrote:
> 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?

You mean calculate this time in some dynamical way and program this
during pre_streamon or s_stream?

If yes, unfortunately hw can't do this.

Regards,
Tommaso

> 
> > +
> > +  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