[libcamera-devel] [PATCH v4 4/5] libcamera: properties: Provide a Devices camera property

[Kieran Bingham]

Quoting Barnabás Pőcze (2023-06-15 22:21:12)
> Hi
> 
> 
> 2023. június 15., csütörtök 19:26 keltezéssel, Kieran Bingham via libcamera-devel <libcamera-devel at lists.libcamera.org> írta:
> 
> > Provide a new Camera property that allows pipeline handlers to list any
> > kernel device used to operate the camera. This allows other frameworks
> > and daemons such as PipeWire to better understand the resources consumed
> > by a Camera and consider ignoring those resources when enumerating
> > camera devices on a system.
> > 
> > Tested-by: Ashok Sidipotu <ashok.sidipotu at collabora.com>
> > Reviewed-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
> > Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > 
> > ---
> > v4:
> >  - Report that different cameras may report identical devices
> >  - Rename to SystemDevices
> > 
> > Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > ---
> >  src/libcamera/property_ids.yaml | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/src/libcamera/property_ids.yaml b/src/libcamera/property_ids.yaml
> > index cb55e0ed2283..ef1dfd322db1 100644
> > --- a/src/libcamera/property_ids.yaml
> > +++ b/src/libcamera/property_ids.yaml
> > @@ -690,6 +690,15 @@ controls:
> >          that is twice that of the full resolution mode. This value will be valid
> >          after the configure method has returned successfully.
> > 
> > +  - SystemDevices:
> > +      type: int64_t
> > +      size: [n]
> > +      description: |
> > +        A list of integer values of type dev_t denoting major and minor device
> > +        number of the underlying devices used in the operation of this camera.
> 
> I am no native speaker of English, but to me any of
> 
>  - ... denoting [the] major and minor device number of the underlying ...
>  - ... denoting major and minor device number[s] of the underlying ...
> 
> sounds a bit better.

Yes, I'll add those.

> 
> 
> > +
> > +        Different cameras may report identical devices.
> 
> I am wondering how this statement is reconciled with the fact that `camerasByDevnum_`
> is just a simple map, and not a multimap; and that `CameraManager::get(dev_t)`
> returns a single camera. I know this is not really relevant for this patch, sorry,
> but maybe it's worth looking into.

Hopefully [0] will remove all concerns about camerasByDevnum_ by
removing it and CameraManager::get(dev_t) entirely.

[0] https://patchwork.libcamera.org/project/libcamera/list/?series=3927

Thanks

Kieran


> 
> 
> > +
> >    # ----------------------------------------------------------------------------
> >    # Draft properties section
> > 
> > --
> > 2.34.1
> 
> 
> Regards,
> Barnabás Pőcze