Re: [PATCH v2 1/8] media: dt-bindings: i2c: Document ov5670

[Sakari Ailus <sakari.ailus@iki.fi>]

On Tue, Mar 15, 2022 at 09:03:41AM +0100, Krzysztof Kozlowski wrote:
> On 15/03/2022 08:59, Sakari Ailus wrote:
> > Hi Krzysztof, Jacopo,
> > 
> > On Tue, Mar 15, 2022 at 08:32:58AM +0100, Krzysztof Kozlowski wrote:
> >> On 14/03/2022 17:27, Jacopo Mondi wrote:
> >>> Provide the bindings documentation for Omnivision OV5670 image sensor.
> >>>
> >>> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> >>>
> >>> ---
> >>> v1->v2 (comments from Krzysztof)
> >>>
> >>> - Rename to include manufacturer name
> >>> - Add entry to MAINTAINERS
> >>> - Add maxItems: to -gpios properties
> >>> - Use common clock properties
> >>> - Use enum: [1, 2] for data lanes
> >>> - Fix whitespace issue in example
> >>> ---
> >>>
> >>>  .../bindings/media/i2c/ovti,ov5670.yaml       | 99 +++++++++++++++++++
> >>>  MAINTAINERS                                   |  1 +
> >>>  2 files changed, 100 insertions(+)
> >>>  create mode 100644 Documentation/devicetree/bindings/media/i2c/ovti,ov5670.yaml
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/media/i2c/ovti,ov5670.yaml b/Documentation/devicetree/bindings/media/i2c/ovti,ov5670.yaml
> >>> new file mode 100644
> >>> index 000000000000..73cf72203f17
> >>> --- /dev/null
> >>> +++ b/Documentation/devicetree/bindings/media/i2c/ovti,ov5670.yaml
> >>> @@ -0,0 +1,99 @@
> >>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> >>> +%YAML 1.2
> >>> +---
> >>> +$id: http://devicetree.org/schemas/media/i2c/ovti,ov5670.yaml#
> >>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>> +
> >>> +title: Omnivision OV5670 5 Megapixels raw image sensor
> >>> +
> >>> +maintainers:
> >>> +  - Jacopo Mondi <jacopo@jmondi.org>
> >>> +
> >>> +description: |-
> >>> +  The OV5670 is a 5 Megapixels raw image sensor which provides images in 10-bits
> >>> +  RAW BGGR Bayer format on a 2 data lanes MIPI CSI-2 serial interface and is
> >>> +  controlled through an I2C compatible control bus.
> >>> +
> >>> +properties:
> >>> +  compatible:
> >>> +    const: ovti,ov5670
> >>> +
> >>> +  reg:
> >>> +    maxItems: 1
> >>> +
> >>> +  assigned-clocks: true
> >>> +  assigned-clock-parents: true
> >>> +  assigned-clock-rates: true
> >>
> >> You should not need these. These are coming with schema. You can add
> >> these to example schema below and double-check.
> > 
> > They should probably be required actually.
> 
> Why required? The hardware can work with different clocks, get their
> rate and configure internal PLLs/clocks to new value. Having it required
> might have sense for current implementation of driver but this is
> independent of bindings. Bindings do not describe driver, but hardware.

We've had this discussion before and the result of that was this (see
"Handling clocks"):

Documentation/driver-api/media/camera-sensor.rst

> 
> >>
> >>> +
> >>> +  clocks:
> >>> +    description: System clock. From 6 to 27 MHz.
> >>> +    maxItems: 1
> >>> +
> >>> +  pwdn-gpios:
> >>> +    description: Reference to the GPIO connected to the PWDNB pin. Active low.
> >>
> >> This does not look like a standard property, so you need a vendor prefix.
> > 
> > The similarly named property exists elsewhere. I wouldn't use a vendor
> > prefix, also for the reason that the functionality is quite common. I guess
> > alternative name would be possible, too --- "shutdown" seems to be more
> > common.
> 
> It exists in three bindings, so it is not a standard property...
> although something closer to standard is "powerdown-gpios" so maybe just
> use that one?

Seems like a better choice.

-- 
Sakari Ailus