Re: [PATCH v3 07/12] dt-bindings: media: Add usb-camera-module

[Conor Dooley <conor@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 5628 bytes --]

On Mon, Sep 29, 2025 at 10:30:35AM +0200, Ricardo Ribalda wrote:
> Hi Conor
> 
> On Fri, 26 Sept 2025 at 18:55, Conor Dooley <conor@kernel.org> wrote:
> >
> > On Fri, Sep 26, 2025 at 01:11:31PM +0000, Ricardo Ribalda wrote:
> > > For fixed cameras modules the OS needs to know where they are mounted.
> > > This information is used to determine if images need to be rotated or
> > > not.
> > >
> > > ACPI has a property for this purpose, which is parsed by
> > > acpi_get_physical_device_location():
> > > https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/06_Device_Configuration/Device_Configuration.html#pld-physical-location-of-device
> > >
> > > In DT we have similar properties for video-interface-devices called
> > > orientation and rotation:
> > > Documentation/devicetree/bindings/media/video-interface-devices.yaml
> > >
> > > Add a new schema that combines usb/usb-device.yaml and
> > > media/video-interface-devices.yaml
> > >
> > > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > > ---
> > >  .../bindings/media/usb-camera-module.yaml          | 46 ++++++++++++++++++++++
> > >  MAINTAINERS                                        |  1 +
> > >  2 files changed, 47 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/media/usb-camera-module.yaml b/Documentation/devicetree/bindings/media/usb-camera-module.yaml
> > > new file mode 100644
> > > index 0000000000000000000000000000000000000000..e4ad6f557b9151751522e49b72ae6584deb0c7ba
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/media/usb-camera-module.yaml
> > > @@ -0,0 +1,46 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/media/usb-camera-module.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: USB Camera Module
> > > +
> > > +maintainers:
> > > +  - Ricardo Ribalda <ribalda@chromium.org>
> > > +
> > > +description: |
> > > +  This schema allows for annotating auxiliary information for fixed camera
> > > +  modules. This information enables the system to determine if incoming frames
> > > +  require rotation, mirroring, or other transformations. It also describes the
> > > +  module's relationship with other hardware elements, such as flash LEDs or
> > > +  Voice Coil Motors (VCMs).
> > > +
> > > +allOf:
> > > +  - $ref: /schemas/usb/usb-device.yaml#
> > > +  - $ref: /schemas/media/video-interface-devices.yaml#
> > > +
> > > +properties:
> > > +  reg:
> > > +    maxItems: 1
> > > +
> >
> > What actually causes this schema to be applied? Did I miss it getting
> > included somewhere?
> 
> I guess your question is why I have not defined the compatible field?
> 
> I tried this change[1] with no luck:
> /usr/local/google/home/ribalda/work/linux/Documentation/devicetree/bindings/media/uvc-camera.example.dtb:
> device@1 (uvc-camera): compatible: ['uvc-camera'] does not contain
> items matching the given schema
> 
> I think it failed, because If we add these allOfs as Rob proposed
> https://lore.kernel.org/all/20250625185608.GA2010256-robh@kernel.org/:
> ```
> allOf:
>   - $ref: /schemas/usb/usb-device.yaml#
>   - $ref: /schemas/media/video-interface-devices.yaml#
> ```
> We cannot (or I do not know how to) have a different compatible than
> the one from usb-device.yaml
> 
> 
> Any suggestion on how to do this properly will be highly appreciated :)

It'd work, I think, if you permitted the pattern from usb-device as a
fallback compatible. I don't know if that would work for whatever niche
you're attempting to fill here though.

Probably a Rob question ultimately.

> 
> Thanks!
> 
> 
> 
> [1]
> 
> @@ -21,10 +21,14 @@ allOf:
>    - $ref: /schemas/media/video-interface-devices.yaml#
> 
>  properties:
> +  compatible:
> +    const: uvc-camera
> +
>    reg:
>      maxItems: 1
> 
>  required:
> +  - compatible
>    - reg
> 
>  additionalProperties: true
> @@ -38,8 +42,8 @@ examples:
>          #size-cells = <0>;
> 
>          device@1 {
> -            compatible = "usb123,4567";
> +           compatible = "uvc-camera";
>              reg = <2>;
>              orientation = <0>;
>              rotation = <90>;
>          };
> 
> >
> > > +required:
> > > +  - reg
> > > +
> > > +additionalProperties: true
> > > +
> > > +examples:
> > > +  - |
> > > +    usb@11270000 {
> > > +        reg = <0x11270000 0x1000>;
> > > +        interrupts = <0x0 0x4e 0x0>;
> > > +        #address-cells = <1>;
> > > +        #size-cells = <0>;
> > > +
> > > +        device@1 {
> > > +            compatible = "usb123,4567";
> > > +            reg = <2>;
> > > +            orientation = <0>;
> > > +            rotation = <90>;
> > > +        };
> > > +    };
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index ee8cb2db483f6a5e96b62b6f2edd05b1427b69f5..1503502a3aed2625e8ff488456ccd7305cc74ba7 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -26258,6 +26258,7 @@ L:    linux-media@vger.kernel.org
> > >  S:   Maintained
> > >  W:   http://www.ideasonboard.org/uvc/
> > >  T:   git git://linuxtv.org/media.git
> > > +F:   Documentation/devicetree/bindings/media/usb-camera-module.yaml
> > >  F:   Documentation/userspace-api/media/drivers/uvcvideo.rst
> > >  F:   Documentation/userspace-api/media/v4l/metafmt-uvc-msxu-1-5.rst
> > >  F:   Documentation/userspace-api/media/v4l/metafmt-uvc.rst
> > >
> > > --
> > > 2.51.0.536.g15c5d4f767-goog
> > >
> 
> 
> 
> --
> Ricardo Ribalda
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]