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Date:   Wed, 15 Apr 2020 18:21:10 +0200
From:   Marco Felsch <m.felsch@pengutronix.de>
To:     Rob Herring <robh@kernel.org>
Cc:     Robert Foss <robert.foss@linaro.org>,
        Dongchun Zhu <dongchun.zhu@mediatek.com>,
        Fabio Estevam <festevam@gmail.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Sakari Ailus <sakari.ailus@iki.fi>,
        Tomasz Figa <tfiga@chromium.org>,
        Maxime Ripard <maxime@cerno.tech>, linux-media@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v7 1/3] media: dt-bindings: ov8856: Document YAML bindings
Message-ID: <20200415162110.bmorj4u4hkqohqjx@pengutronix.de>
References: <20200408110816.2712841-1-robert.foss@linaro.org>
 <20200408110816.2712841-2-robert.foss@linaro.org>
 <20200415160729.GA4438@bogus>
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On 20-04-15 11:07, Rob Herring wrote:
> On Wed, Apr 08, 2020 at 01:08:14PM +0200, Robert Foss wrote:
> > From: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > 
> > This patch adds documentation of device tree in YAML schema for the
> > OV8856 CMOS image sensor.
> > 
> > Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > Signed-off-by: Robert Foss <robert.foss@linaro.org>
> > ---
> > 
> > - Changes since v6:
> >   * Marco: remove qcom specifics from DT example
> >    
> > - Changes since v5:
> >   * Add assigned-clocks and assigned-clock-rates
> >   * robher: dt-schema errors
> > 
> > - Changes since v4:
> >   * Fabio: Change reset-gpio to GPIO_ACTIVE_LOW, explain in description
> >   * Add clock-lanes property to example
> >   * robher: Fix syntax error in devicetree example
> > 
> > - Changes since v3:
> >   * robher: Fix syntax error
> >   * robher: Removed maxItems
> >   * Fixes yaml 'make dt-binding-check' errors
> > 
> > - Changes since v2:
> >   Fixes comments from from Andy, Tomasz, Sakari, Rob.
> >   * Convert text documentation to YAML schema.
> > 
> > - Changes since v1:
> >   Fixes comments from Sakari, Tomasz
> >   * Add clock-frequency and link-frequencies in DT
> > 
> >  .../devicetree/bindings/media/i2c/ov8856.yaml | 143 ++++++++++++++++++
> >  MAINTAINERS                                   |   1 +
> >  2 files changed, 144 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/media/i2c/ov8856.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/media/i2c/ov8856.yaml b/Documentation/devicetree/bindings/media/i2c/ov8856.yaml
> > new file mode 100644
> > index 000000000000..96bef5403d7e
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/media/i2c/ov8856.yaml
> > @@ -0,0 +1,143 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +# Copyright (c) 2019 MediaTek Inc.
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/media/i2c/ov8856.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Omnivision OV8856 CMOS Sensor Device Tree Bindings
> > +
> > +maintainers:
> > +  - Ben Kao <ben.kao@intel.com>
> > +  - Dongchun Zhu <dongchun.zhu@mediatek.com>
> > +
> > +description: |-
> > +  The Omnivision OV8856 is a high performance, 1/4-inch, 8 megapixel, CMOS
> > +  image sensor that delivers 3264x2448 at 30fps. It provides full-frame,
> > +  sub-sampled, and windowed 10-bit MIPI images in various formats via the
> > +  Serial Camera Control Bus (SCCB) interface. This chip is programmable
> > +  through I2C and two-wire SCCB. The sensor output is available via CSI-2
> > +  serial data output (up to 4-lane).
> > +
> > +properties:
> > +  compatible:
> > +    const: ovti,ov8856
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    maxItems: 1
> > +
> > +  clock-names:
> > +    description:
> > +      Input clock for the sensor.
> > +    items:
> > +      - const: xvclk
> > +
> > +  assigned-clocks:
> > +    description:
> > +      Input clock for the sensor.
> > +
> > +  assigned-clock-rates:
> > +    description:
> > +      Frequency of the xvclk clock in Hertz.
> 
> These 2 should have a 'maxItems: 1'

Don't know why those properties are needed here.. IMHO this shouldn't be
part of the binding or at least it should be optional and not required.
All we need is the clocks and the clock-names property.

> > +  dovdd-supply:
> > +    description:
> > +      Definition of the regulator used as interface power supply.
> > +
> > +  avdd-supply:
> > +    description:
> > +      Definition of the regulator used as analog power supply.
> > +
> > +  dvdd-supply:
> > +    description:
> > +      Definition of the regulator used as digital power supply.
> > +
> > +  reset-gpios:
> > +    description:
> > +      The phandle and specifier for the GPIO that controls sensor reset.
> > +      This corresponds to the hardware pin XSHUTDOWN which is physically
> > +      active low.
> > +
> > +  port:
> > +    type: object
> > +    additionalProperties: false
> > +    description:
> > +      A node containing input and output port nodes with endpoint definitions
> 
> Only an output, right?
> 
> > +      as documented in
> > +      Documentation/devicetree/bindings/media/video-interfaces.txt
> > +
> > +    properties:
> > +      endpoint:
> > +        type: object
> > +
> > +        properties:
> > +          clock-lanes:
> > +            maxItems: 1
> > +
> > +          data-lanes:
> > +            maxItems: 1
> > +
> > +          remote-endpoint: true
> > +
> > +        required:
> > +          - clock-lanes
> > +          - data-lanes
> > +          - remote-endpoint
> > +
> > +    required:
> > +      - endpoint
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - clocks
> > +  - clock-names
> > +  - assigned-clocks
> > +  - assigned-clock-rates
> > +  - dovdd-supply
> > +  - avdd-supply
> > +  - dvdd-supply
> > +  - reset-gpios
> > +  - port
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +
> > +    i2c {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        ov8856: camera@10 {
> > +            compatible = "ovti,ov8856";
> > +            reg = <0x10>;
> > +
> > +            reset-gpios = <&pio 111 GPIO_ACTIVE_LOW>;
> > +            pinctrl-names = "default";
> > +            pinctrl-0 = <&clk_24m_cam>;
> > +
> > +            clocks = <&cam_osc>;
> > +            clock-names = "xvclk";
> > +            assigned-clocks = <&cam_osc>;
> > +            assigned-clock-rates = <19200000>;
> > +
> > +            avdd-supply = <&mt6358_vcama2_reg>;
> > +            dvdd-supply = <&mt6358_vcamd_reg>;
> > +            dovdd-supply = <&mt6358_vcamio_reg>;
> > +
> > +            port {
> > +                wcam_out: endpoint {
> > +                    remote-endpoint = <&mipi_in_wcam>;
> > +                    clock-lanes = <0>;
> > +                    data-lanes = <1 2 3 4>;
> > +                    link-frequencies = /bits/ 64 <360000000 180000000>;
> > +                };
> > +            };
> > +        };
> > +    };
> > +...
> > \ No newline at end of file
> 
> ^^^
> 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 534a8dc4f84a..3f35c6e9700a 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -12465,6 +12465,7 @@ L:	linux-media@vger.kernel.org
> >  T:	git git://linuxtv.org/media_tree.git
> >  S:	Maintained
> >  F:	drivers/media/i2c/ov8856.c
> > +F:	Documentation/devicetree/bindings/media/i2c/ov8856.yaml
> >  
> >  OMNIVISION OV9650 SENSOR DRIVER
> >  M:	Sakari Ailus <sakari.ailus@linux.intel.com>
> > -- 
> > 2.25.1
> > 
> 

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