[PATCH 2/4] ipa: libipa: Copy pwl from rpi

[Laurent Pinchart]

On Fri, May 31, 2024 at 11:34:15AM +0100, Kieran Bingham wrote:
> Quoting Paul Elder (2024-04-26 08:39:39)
> > Hi Naush,
> > 
> > On Mon, Apr 08, 2024 at 09:14:41AM +0100, Naushir Patuck wrote:
> > > Hi Paul,
> > > 
> > > On Fri, 5 Apr 2024 at 09:03, Paul Elder <paul.elder at ideasonboard.com> wrote:
> > > >
> > > > Copy the piecewise linear function code from Raspberry Pi.
> > > >
> > > 
> > > This seems like a good time to mention something I was intending on
> > > doing for a while...
> > > 
> > > Our PWL library is used internally in a few places
> > > (libcamera/libpisp/rpicam-apps/some internal tools).  Right now each
> > > of these libraries has a copy of pretty much the same pwl.c/pwl.h
> > > file.  I was intending to create a stand alone Raspberry Pi PWL
> > > library that could be linked with these so we only have one canonical
> > > copy of the source code.  This could then be included into
> > > libcamera/libpipa as a subproject if needed.  Do you think this would
> > > be helpful and suitable for you?  We will need to look at possibly
> > 
> > Yeah that might be a good idea. (although I'm not in the position to
> > make these decisions)
> 
> I don't think core libcamera can rely on a 'subproject' (in meson terms)
> as packagers/distributions will not accept a build that has to go and
> download more code to perform the build.
> 
> But we should certainly find a way to reduce having 2, 3, 4 copies of
> the same code in different places...
> 
> I think the Pwl is small enough (and stable enough) that it's not too
> painful for now. I wonder if we do need to break out more like we have
> with libcamera-base ... but I don't know where the bar is for that yet.

I would vote for a standalone math library that would be optimized for
camera usage, but I fear we would be reinventing the wheel :-)

> > In any case we need this right now so for now we'll go with this :)

-- 
Regards,

Laurent Pinchart