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From:   Mikhail Rudenko <mike.rudenko@gmail.com>
To:     Tommaso Merciai <tommaso.merciai@amarulasolutions.com>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Jacopo Mondi <jacopo@jmondi.org>,
        Shawn Tu <shawnx.tu@intel.com>,
        Christian Hemp <c.hemp@phytec.de>,
        Arec Kao <arec.kao@intel.com>, Arnd Bergmann <arnd@arndb.de>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Daniel Scally <djrscally@gmail.com>,
        Jimmy Su <jimmy.su@intel.com>, linux-media@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] media: dt-bindings: media: i2c: document OV4689
 DT bindings
Date:   Fri, 16 Sep 2022 16:42:25 +0300
In-reply-to: <20220916131544.GA2701@tom-ThinkPad-T14s-Gen-2i>
Message-ID: <871qsbph75.fsf@gmail.com>
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On 2022-09-16 at 15:15 +02, Tommaso Merciai <tommaso.merciai@amarulasolutions.com> wrote:
> Hi Mikhail,
>
> On Thu, Sep 15, 2022 at 11:11:57PM +0300, Mikhail Rudenko wrote:
>>
>> Hi Tommaso,
>>
>> On 2022-09-13 at 16:05 +02, Tommaso Merciai <tommaso.merciai@amarulasolutions.com> wrote:
>> > Hi Mikhail,
>> >
>> > On Sun, Sep 11, 2022 at 11:01:34PM +0300, Mikhail Rudenko wrote:
>> >> Add device-tree binding documentation for OV4689 image sensor driver,
>> >> and the relevant MAINTAINERS entries.
>> >>
>> >> Signed-off-by: Mikhail Rudenko <mike.rudenko@gmail.com>
>> >> ---
>> >>  .../bindings/media/i2c/ovti,ov4689.yaml       | 141 ++++++++++++++++++
>> >>  MAINTAINERS                                   |   7 +
>> >>  2 files changed, 148 insertions(+)
>> >>  create mode 100644 Documentation/devicetree/bindings/media/i2c/ovti,ov4689.yaml
>> >>
>> >> diff --git a/Documentation/devicetree/bindings/media/i2c/ovti,ov4689.yaml b/Documentation/devicetree/bindings/media/i2c/ovti,ov4689.yaml
>> >> new file mode 100644
>> >> index 000000000000..376330b5572a
>> >> --- /dev/null
>> >> +++ b/Documentation/devicetree/bindings/media/i2c/ovti,ov4689.yaml
>> >> @@ -0,0 +1,141 @@
>> >> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> >> +%YAML 1.2
>> >> +---
>> >> +$id: http://devicetree.org/schemas/media/i2c/ovti,ov4689.yaml#
>> >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> >> +
>> >> +title: Omnivision OV4689 CMOS
>> >> +
>> >> +maintainers:
>> >> +  - Mikhail Rudenko <mike.rudenko@gmail.com>
>> >> +
>> >> +description: |
>> >> +  The Omnivision OV4689 is a high performance, 1/3-inch, 4 megapixel
>> >> +  image sensor. Ihis chip supports high frame rate speeds up to 90 fps
>> >> +  at 2688x1520 resolution. It is programmable through an I2C
>> >> +  interface, and sensor output is sent via 1/2/4 lane MIPI CSI-2
>> >> +  connection.
>> >> +
>> >> +allOf:
>> >> +  - $ref: /schemas/media/video-interface-devices.yaml#
>> >> +
>> >> +properties:
>> >> +  compatible:
>> >> +    const: ovti,ov4689
>> >> +
>> >> +  reg:
>> >> +    maxItems: 1
>> >> +
>> >> +  clocks:
>> >> +    description:
>> >> +      External clock (XVCLK) for the sensor, 6-64 MHz
>> >> +    maxItems: 1
>> >> +
>> >> +  clock-names: true
>> >> +
>> >> +  dovdd-supply:
>> >> +    description:
>> >> +      Digital I/O voltage supply, 1.7-3.0 V
>> >> +
>> >> +  avdd-supply:
>> >> +    description:
>> >> +      Analog voltage supply, 2.6-3.0 V
>> >> +
>> >> +  dvdd-supply:
>> >> +    description:
>> >> +      Digital core voltage supply, 1.1-1.3 V
>> >> +
>> >> +  powerdown-gpios:
>> >> +    maxItems: 1
>> >> +    description:
>> >> +      GPIO connected to the powerdown pin (active low)
>> >> +
>> >> +  reset-gpios:
>> >> +    maxItems: 1
>> >> +    description:
>> >> +      GPIO connected to the reset pin (active low)
>> >> +
>> >> +  orientation: true
>> >> +
>> >> +  rotation: true
>> >> +
>> >> +  port:
>> >> +    $ref: /schemas/graph.yaml#/$defs/port-base
>> >> +    additionalProperties: false
>> >> +    description:
>> >> +      Output port node, single endpoint describing the CSI-2 transmitter
>> >> +
>> >> +    properties:
>> >> +      endpoint:
>> >> +        $ref: /schemas/media/video-interfaces.yaml#
>> >> +        unevaluatedProperties: false
>> >> +
>> >> +        properties:
>> >> +          data-lanes:
>> >> +            oneOf:
>> >> +              - items:
>> >> +                  - const: 1
>> >> +                  - const: 2
>> >> +                  - const: 3
>> >> +                  - const: 4
>> >> +              - items:
>> >> +                  - const: 1
>> >> +                  - const: 2
>> >> +              - items:
>> >> +                  - const: 1
>> >> +          link-frequencies: true
>> >> +
>> >> +        required:
>> >> +          - data-lanes
>> >> +          - link-frequencies
>> >> +
>> >> +required:
>> >> +  - compatible
>> >> +  - reg
>> >> +  - clocks
>> >> +  - clock-names
>> >> +  - dovdd-supply
>> >> +  - avdd-supply
>> >> +  - dvdd-supply
>> >> +  - powerdown-gpios
>> >> +  - reset-gpios
>> >> +  - port
>> >
>> > I think we don't need all of these entries as required.
>> > The only let me say "really" required are:
>> >
>> > - compatible
>> > - reg
>> > - clocks
>> > - port
>>
>> Thanks for the review! I agree that the driver may be modified to work
>> without powerdown and reset gpios and they are not required for sensor
>> operation. On contrary, supplies are obviously required. Of course, linux
>> provides dummy regulators if supplies are missing from device tree, but
>> I though the intention was to document hardware, not implementation
>> details. What do think of this?
>
> We have already discuss on this on the following thread sometimes ago :)
>
> https://www.patchwork.linux-fancy.com/project/linux-fancy/patch/20220630134835.592521-6-tommaso.merciai@amarulasolutions.com/
>
> Take a look and let me know.

Okay, if there already is a consensus regarding this matter, I'll make
the regulators optional in v3.

--
Best regards,
Mikhail Rudenko