Re: [V9, 1/2] media: dt-bindings: media: i2c: Document OV02A10 bindings

[Dongchun Zhu <dongchun.zhu@mediatek.com>]

Hi Rob,

On Wed, 2020-05-27 at 09:27 -0600, Rob Herring wrote:
> On Wed, May 27, 2020 at 2:51 AM Dongchun Zhu <dongchun.zhu@mediatek.com> wrote:
> >
> > Hi Rob,
> >
> > Thanks for the review. Please see my replies below.
> >
> > On Tue, 2020-05-26 at 12:28 -0600, Rob Herring wrote:
> > > On Sat, May 23, 2020 at 04:41:02PM +0800, Dongchun Zhu wrote:
> > > > Add DT bindings documentation for Omnivision OV02A10 image sensor.
> > > >
> > > > Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > > > ---
> > > >  .../bindings/media/i2c/ovti,ov02a10.yaml           | 172 +++++++++++++++++++++
> > > >  MAINTAINERS                                        |   7 +
> > > >  2 files changed, 179 insertions(+)
> > > >  create mode 100644 Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml b/Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml
> > > > new file mode 100644
> > > > index 0000000..56f31b5
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml
> > > > @@ -0,0 +1,172 @@
> > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > > +# Copyright (c) 2020 MediaTek Inc.
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: http://devicetree.org/schemas/media/i2c/ovti,ov02a10.yaml#
> > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > +
> > > > +title: Omnivision OV02A10 CMOS Sensor Device Tree Bindings
> > > > +
> > > > +maintainers:
> > > > +  - Dongchun Zhu <dongchun.zhu@mediatek.com>
> > > > +
> > > > +description: |-
> > > > +  The Omnivision OV02A10 is a low-cost, high performance, 1/5-inch, 2 megapixel
> > > > +  image sensor, which is the latest production derived from Omnivision's CMOS
> > > > +  image sensor technology. Ihis chip supports high frame rate speeds up to 30fps
> > > > +  @ 1600x1200 (UXGA) resolution transferred over a 1-lane MIPI interface. The
> > > > +  sensor output is available via CSI-2 serial data output.
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    const: ovti,ov02a10
> > > > +
> > > > +  reg:
> > > > +    maxItems: 1
> > > > +
> > > > +  clocks:
> > > > +    items:
> > > > +      - description: top mux camtg clock
> > > > +      - description: divider clock
> > > > +
> > > > +  clock-names:
> > > > +    items:
> > > > +      - const: eclk
> > > > +      - const: freq_mux
> > > > +
> > > > +  clock-frequency:
> > > > +    description:
> > > > +      Frequency of the eclk clock in Hertz.
> > > > +
> >
> > Rob, shall we use 'maxItems: 1' to constrain property: clock-frequency?
> 
> No, because it is a scalar, not an array.
> 

Got it.

> > Or could we adopt 'clock-frequency: true' directly here?
> 
> As-is is fine.
> 

Understood.

> > > > +  dovdd-supply:
> > > > +    description:
> > > > +      Definition of the regulator used as Digital I/O voltage supply.
> > > > +
> >
> > Shall we add 'maxItems: 1' here?
> 
> No, supplies are always singular.
> 

Fine.

> >
> > > > +  avdd-supply:
> > > > +    description:
> > > > +      Definition of the regulator used as Analog voltage supply.
> > > > +
> >
> > Ditto.
> >
> > > > +  dvdd-supply:
> > > > +    description:
> > > > +      Definition of the regulator used as Digital core voltage supply.
> > > > +
> >
> > Ditto.
> >
> > > > +  powerdown-gpios:
> > > > +    description:
> > > > +      Must be the device tree identifier of the GPIO connected to the
> > > > +      PD_PAD pin. This pin is used to place the OV02A10 into Standby mode
> > > > +      or Shutdown mode. As the line is active low, it should be
> > > > +      marked GPIO_ACTIVE_LOW.
> > >
> > > Need to define how many GPIOs ('maxItems: 1')
> > >
> >
> > It would be fixed like this in next release.
> > powerdown-gpios:
> >   maxItems: 1
> >   description:
> >     Must be the device tree identifier of the GPIO connected to the
> >     PD_PAD pin. This pin is used to place the OV02A10 into Standby mode
> >     or Shutdown mode. As the line is active low, it should be
> >     marked GPIO_ACTIVE_LOW.
> >

Tomasz, I don't know whether you noticed this description.
Here I simply defined one necessary GPIO polarity in DT which driver
settings need to follow.

> > > > +
> > > > +  reset-gpios:
> > > > +    description:
> > > > +      Must be the device tree identifier of the GPIO connected to the
> > > > +      RST_PD pin. If specified, it will be asserted during driver probe.
> > > > +      As the line is active high, it should be marked GPIO_ACTIVE_HIGH.
> > >
> > > Here too.
> > >
> >
> > Similar as 'powerdown-gpios'.
> > Fixed in next release.
> >
> > > > +
> > > > +  rotation:
> > > > +    description:
> > > > +      Definition of the sensor's placement.
> > > > +    allOf:
> > > > +      - $ref: "/schemas/types.yaml#/definitions/uint32"
> > > > +      - enum:
> > > > +          - 0    # Sensor Mounted Upright
> > > > +          - 180  # Sensor Mounted Upside Down
> > > > +        default: 0
> > > > +
> > > > +  ovti,mipi-tx-speed:
> > > > +    description:
> > > > +      Indication of MIPI transmission speed select, which is to control D-PHY
> > > > +      timing setting by adjusting MIPI clock voltage to improve the clock
> > > > +      driver capability.
> > > > +    allOf:
> > > > +      - $ref: "/schemas/types.yaml#/definitions/uint32"
> > > > +      - enum:
> > > > +          - 0    #  20MHz -  30MHz
> > > > +          - 1    #  30MHz -  50MHz
> > > > +          - 2    #  50MHz -  75MHz
> > > > +          - 3    #  75MHz - 100MHz
> > > > +          - 4    # 100MHz - 130MHz
> > > > +        default: 3
> > > > +
> > > > +  # See ../video-interfaces.txt for details
> > > > +  port:
> > > > +    type: object
> > > > +    additionalProperties: false
> > >
> > > Should have a description of what data the port has.
> > >
> >
> > It would be updated as below in next release.
> > port:
> >   type: object
> >   additionalProperties: false
> >   description:
> >     Input port node, single endpoint describing the CSI-2 transmitter.
> 
> Output?
> 

Sorry for the typo.
Yes, this should be output port node.

> >
> > > > +
> > > > +    properties:
> > > > +      endpoint:
> > > > +        type: object
> > > > +        additionalProperties: false
> > > > +
> > > > +        properties:
> >
> > Actually I wonder whether we need to declare 'clock-lanes' here?
> 
> Yes, if you are using it.
> 

Looking back to the upstreamed patches, it seems that there is a deep
divide in the setting of 'clock-lanes' property.

As the last comment I just posed, for OV02A10, 'clock-lanes' should be
set to <0> (clock lane on hardware lane 0).
But here we may follow IMX219 patch, which removed 'clock-lanes'
property due to the fact that sensor hardware does not support lane
reordering.

Rob, Sakari, what's your opinions?

> Rob