Re: [PATCH v5 1/2] media: dt-bindings: Add OmniVision OV64A40

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Jacopo,

On Thu, Dec 07, 2023 at 11:42:35AM +0100, Jacopo Mondi wrote:
> Hi Sakari
> 
> On Thu, Dec 07, 2023 at 10:35:03AM +0000, Sakari Ailus wrote:
> > Hi Jacopo,
> >
> > On Thu, Dec 07, 2023 at 11:13:21AM +0100, Jacopo Mondi wrote:
> > > Hi Sakari
> > >
> > > On Thu, Dec 07, 2023 at 09:57:06AM +0000, Sakari Ailus wrote:
> > > > Hi Jacopo,
> > > >
> > > > On Wed, Dec 06, 2023 at 04:58:59PM +0100, Jacopo Mondi wrote:
> > > > > Add bindings for OmniVision OV64A40.
> > > > >
> > > > > Co-developed-by: Lee Jackson <lee.jackson@arducam.com>
> > > > > Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > > > > Acked-by: Conor Dooley <conor.dooley@microchip.com>
> > > > > ---
> > > > >  .../bindings/media/i2c/ovti,ov64a40.yaml      | 97 +++++++++++++++++++
> > > > >  1 file changed, 97 insertions(+)
> > > > >  create mode 100644 Documentation/devicetree/bindings/media/i2c/ovti,ov64a40.yaml
> > > > >
> > > > > diff --git a/Documentation/devicetree/bindings/media/i2c/ovti,ov64a40.yaml b/Documentation/devicetree/bindings/media/i2c/ovti,ov64a40.yaml
> > > > > new file mode 100644
> > > > > index 000000000000..e6c9d540a2dd
> > > > > --- /dev/null
> > > > > +++ b/Documentation/devicetree/bindings/media/i2c/ovti,ov64a40.yaml
> > > > > @@ -0,0 +1,97 @@
> > > > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > > > +%YAML 1.2
> > > > > +---
> > > > > +$id: http://devicetree.org/schemas/media/i2c/ovti,ov64a40.yaml#
> > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > > +
> > > > > +title: OmniVision OV64A40 Image Sensor
> > > > > +
> > > > > +maintainers:
> > > > > +  - Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > > > > +
> > > > > +allOf:
> > > > > +  - $ref: /schemas/media/video-interface-devices.yaml#
> > > > > +
> > > > > +properties:
> > > > > +  compatible:
> > > > > +    const: ovti,ov64a40
> > > > > +
> > > > > +  reg:
> > > > > +    maxItems: 1
> > > > > +
> > > > > +  clocks:
> > > > > +    maxItems: 1
> > > > > +
> > > > > +  avdd-supply:
> > > > > +    description: Analog voltage supply, 2.8 volts
> > > > > +
> > > > > +  dvdd-supply:
> > > > > +    description: Digital core voltage supply, 1.1 volts
> > > > > +
> > > > > +  dovdd-supply:
> > > > > +    description: Digital I/O voltage supply, 1.8 volts
> > > > > +
> > > > > +  powerdown-gpios:
> > > > > +    maxItems: 1
> > > > > +
> > > > > +  reset-gpios:
> > > > > +    maxItems: 1
> > > > > +
> > > > > +  port:
> > > > > +    $ref: /schemas/graph.yaml#/$defs/port-base
> > > > > +    additionalProperties: false
> > > > > +
> > > > > +    properties:
> > > > > +      endpoint:
> > > > > +        $ref: /schemas/media/video-interfaces.yaml#
> > > > > +        additionalProperties: false
> > > > > +
> > > > > +        properties:
> > > > > +          bus-type:
> > > > > +            enum:
> > > > > +              - 1 # MIPI CSI-2 C-PHY
> > > > > +              - 4 # MIPI CSI-2 D-PHY
> > > > > +          data-lanes: true
> > > > > +          link-frequencies: true
> > > > > +          clock-noncontinuous: true
> > > > > +          remote-endpoint: true
> > > > > +
> > > > > +required:
> > > > > +  - compatible
> > > > > +  - reg
> > > > > +  - clocks
> > > > > +  - port
> > > > > +
> > > > > +unevaluatedProperties: false
> > > > > +
> > > > > +examples:
> > > > > +  - |
> > > > > +      #include <dt-bindings/gpio/gpio.h>
> > > > > +
> > > > > +      i2c {
> > > > > +          #address-cells = <1>;
> > > > > +          #size-cells = <0>;
> > > > > +
> > > > > +          camera@36 {
> > > > > +              compatible = "ovti,ov64a40";
> > > > > +              reg = <0x36>;
> > > > > +              clocks = <&camera_clk>;
> > > > > +              dovdd-supply = <&vgen4_reg>;
> > > > > +              avdd-supply = <&vgen3_reg>;
> > > > > +              dvdd-supply = <&vgen2_reg>;
> > > > > +              powerdown-gpios = <&gpio1 9 GPIO_ACTIVE_HIGH>;
> > > > > +              reset-gpios = <&gpio1 10 GPIO_ACTIVE_LOW>;
> > > > > +              rotation = <180>;
> > > > > +              orientation = <2>;
> > > > > +
> > > > > +              port {
> > > > > +                  endpoint {
> > > > > +                      remote-endpoint = <&mipi_csi2_in>;
> > > > > +                      bus-type = <4>;
> > > > > +                      data-lanes = <1 2 3 4>;
> > > >
> > > > This is missing link-frequencies.
> > > >
> > >
> > > I was not sure about this, in facts.
> > >
> > > Bindings are about HW while link-frequencies is only about restricting
> > > how the driver configures the sensor. Thus, I've not listed it as
> > > mandatory however the driver mandates its presence.
> > >
> > > Should I make it mandatory in bindings ?
> >
> > See
> > <URL:https://hverkuil.home.xs4all.nl/spec/driver-api/camera-sensor.html#handling-clocks>.
> >
> > IOW it's about the driver, too, but only secondarily.
> >
> 
> Should link-frequencies be made mandatory by video-interfaces.yaml if
> the bus type is CSI-2 (D-PHY as well as C-PHY I presume ?)

Works for me. There are certainly old bindings that don't have it at all so
there would be warnings. Some drivers support just a single frequency,
that's often the case with register list based drivers so things work just
fine until someone goes and adds another to support a different system.

-- 
Regards,

Sakari Ailus