[libcamera-devel] [PATCH 2/3] libcamera: camera_sensor: Set default sensor location to Unknown

[Niklas Söderlund]

Hi Laurent,

On 2021-02-11 23:44:44 +0200, Laurent Pinchart wrote:
> Hi Paul,
> 
> Thank you for the patch.
> 
> On Thu, Feb 11, 2021 at 02:24:19PM +0100, Niklas Söderlund wrote:
> > On 2021-02-11 17:55:26 +0900, Paul Elder wrote:
> > > Instead of choosing some arbitrary location for the sensor when its
> > > location is unknown, set it explicitly to unknown.
> > > 
> > > Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> > > ---
> > >  src/libcamera/camera_sensor.cpp | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
> > > index c9e8d49b..474055ba 100644
> > > --- a/src/libcamera/camera_sensor.cpp
> > > +++ b/src/libcamera/camera_sensor.cpp
> > > @@ -446,7 +446,7 @@ int CameraSensor::initProperties()
> > >  			break;
> > >  		}
> > >  	} else {
> > > -		propertyValue = properties::CameraLocationExternal;
> > > +		propertyValue = properties::CameraLocationUnknown;
> > 
> > I wonder if it would not make more sens to just set the location to 
> > front here? What additional use-case do we cover by adding the unkown 
> > location?
> >
> > If we want to highlight we don't know where a camera is would it not be 
> > better to LOG() that we don't know but assume front. I'm thinking from 
> > an application point of view is it not kind of messy to have to deal 
> > with a firmware description that is incomplete? I guess all users will 
> > do what you do in this series for the HAL and default it to something 
> > else.
> 
> Isn't it better to let the application decide though, instead of
> pretending we know ? The application could then decide how to deal with
> the situation depending on its use cases, which are not known to
> libcamera.

I'd say it depends :-)

Down the road I envision the camera location to always be mandatory.  
Either read from firmware or a platform configuration file. If this 
holds true I think adding a unknown location now is just pushing the 
problem down the road. On the other hand if we think we will have 
cameras with an unknown location and see it as a valid use-case I think 
this patch is correct.

I'm however not convinced we have a good use-case for a camera with an 
unknown location. Do you have an example of such use-case?

> 
> > If you do opt to keep the addition of CameraLocationUnknown you should 
> > also update cam utility to handle the new location value.
> 
> Yes, that should be part of this series.
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> 
> > >  	}
> > >  	properties_.set(properties::Location, propertyValue);
> > >  
> 
> -- 
> Regards,
> 
> Laurent Pinchart

-- 
Regards,
Niklas Söderlund