[libcamera-devel] Mandatory camera properties

[Laurent Pinchart]

On Thu, Aug 20, 2020 at 01:36:33PM +0000, Umang Jain wrote:
> Hi Niklas,
> 
> A few thoughts below,
> 
> On 8/20/20 12:53 PM, Niklas Söderlund wrote:
> > Hello,
> >
> > While reading the hot-plug series and with my recent work on
> > user-friendly names discussions on camera properties have been touch
> > upon. Before working on adding a check to disallow registering a camera
> > that does not have all these properties I think it's a good idea we
> > agree on which ones are mandatory.
>
> Yes, most of it sounds in the right direction.
> However, I think adding a check to disallow registering a camera
> that doesn't have mandatory properties, might be a bit harsh, no?

I think it's indeed a bit harsh. From a development point of view, being
able to register a camera before all properties are in place is useful.
Requiring a 100% complete implementation of a pipeline handler before
anything can be tested wouldn't be developer-friendly. I'd rather catch
this with a compliance tool.

> What I can of think of, as of now, is a reference from exif metadata
> work, I came across exif_data_fix() [1] which might be a useful reference.
> It will have a fallback value to mandatory properties, so that a camera
> can be registered and the user can be warned/informed of what's "missing"
> that libcamera expects.
> 
> > After reading the current discussions and whats in master it seems we
> > wish to make Location but not Rotation mandatory, is this correct? If so
> > shall we remove the Rotation fallback (set to 0) in CameraSensor?
> >
> > Looking a head I thin we also would like to make the (hopefully)
> > upcoming Model property mandatory?
> >
> > I see no urgency to lock this all down but as we move to do more work
> > involving properties I think its time we start to think about if we want
> > to make some of them mandatory.
>
> [1]: 
> https://libexif.github.io/api/exif-data_8h.html#a9146930a0b3ef89375790e19e1bc55b2 

-- 
Regards,

Laurent Pinchart