[libcamera-devel] [PATCH v3 4/5] libcamera: properties: Provide a Devices camera property

[Barnabás Pőcze]

Hi


2023. június 12., hétfő 19:44 keltezéssel, Laurent Pinchart <laurent.pinchart at ideasonboard.com> írta:

> [...]
> > > > diff --git a/src/libcamera/property_ids.yaml b/src/libcamera/property_ids.yaml
> > > > index cb55e0ed2283..6141942969f9 100644
> > > > --- a/src/libcamera/property_ids.yaml
> > > > +++ b/src/libcamera/property_ids.yaml
> > > > @@ -690,6 +690,13 @@ controls:
> > > >          that is twice that of the full resolution mode. This value will be valid
> > > >          after the configure method has returned successfully.
> > > >
> > > > +  - Devices:
> > > > +      type: int64_t
> > >
> > > I am wondering why the type is `int64_t`. POSIX only says `dev_t` is an integer type[0].
> > > Both glibc[1] and musl[2] define it as an unsigned (64-bit) integer (at least as far as I checked).
> >
> > Indeed every implementation I can see define it as a 64-bit, but the
> > kernel uses only 32 bits.
> >
> > This is a libcamera control limitation ultimately, as we don't have
> > unsigned integer controls. I'm not sure yet if adding would be helpful
> > or difficult. It might be worth trying out.
> 
> An int64_t makes sure it will always fit the dev_t value regardless of
> the platform, so I don't really see much added value in adding a
> platform-dependent integer type for controls.
> [...]

I did not mean to imply that the size should be platform dependent.
Just that I would have used uint64_t probably, but at that time
I was not aware that libcamera had no uint controls.


Regards,
Barnabás Pőcze