[PATCH 2/7] libcamera: mali-c55: Enable usage of scaler

[Jacopo Mondi]

Hi Kieran

On Thu, Jun 13, 2024 at 08:25:43PM GMT, Kieran Bingham wrote:
> Quoting Daniel Scally (2024-06-13 16:59:44)
> > From: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
> >
> > The Mali C55 ISP has a resizing pipeline that allows to crop and scale
> > images.
> >
> > So far the mali-c55 pipeline has only supported cropping without using
> > the scaling functionalities.
> >
> > Now that the kernel has gained support for the scaling operations, make
> > the libcamera pipeline use it by combining it with a first cropping step
> > to align the input and output images FOV ratio, and then scale to the
> > desired output size.
> >
> > Signed-off-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
>
> Missing SoB.
>
> > ---
> >  src/libcamera/pipeline/mali-c55/mali-c55.cpp | 18 +++++++++++++++---
> >  1 file changed, 15 insertions(+), 3 deletions(-)
> >
> > diff --git a/src/libcamera/pipeline/mali-c55/mali-c55.cpp b/src/libcamera/pipeline/mali-c55/mali-c55.cpp
> > index 9442d17c..c4f1afbc 100644
> > --- a/src/libcamera/pipeline/mali-c55/mali-c55.cpp
> > +++ b/src/libcamera/pipeline/mali-c55/mali-c55.cpp
> > @@ -715,16 +715,28 @@ int PipelineHandlerMaliC55::configureProcessedStream(MaliC55CameraData *data,
> >         if (ret)
> >                 return ret;
> >
> > -       /* \todo Configure the resizer crop/compose rectangles. */
> > -       Rectangle ispCrop = { 0, 0, config.size };
> > +       /*
> > +        * Compute the scaler-in to scaler-out ratio: first center-crop to align
> > +        * the FOV to the desired resolution, then scale to the desired size.
> > +        */
> > +       Size scalerIn = subdevFormat.size.boundedToAspectRatio(config.size);
> > +       int xCrop = (subdevFormat.size.width - scalerIn.width) / 2;
> > +       int yCrop = (subdevFormat.size.height - scalerIn.height) / 2;
> > +       Rectangle ispCrop = { xCrop, yCrop, scalerIn };
>
> Don't we have geometry helpers to do centering like this?
>

Our helpers allow to center a Size in a Point:

	Rectangle centeredTo(const Point &center) const;

Here I have a size obtained by rounding down a rectangle's dimention
to an aspect ratio, and I'm just creating a rectangle out of it,
centered in the original one.

I could create an helper that does that, but sincerely, it's really
two lines of code.

> >         ret = pipe->resizer->setSelection(0, V4L2_SEL_TGT_CROP, &ispCrop);
> >         if (ret)
> >                 return ret;
> >
> > -       ret = pipe->resizer->setSelection(0, V4L2_SEL_TGT_COMPOSE, &ispCrop);
> > +       Rectangle ispCompose = { 0, 0, config.size };
> > +       ret = pipe->resizer->setSelection(0, V4L2_SEL_TGT_COMPOSE, &ispCompose);
> >         if (ret)
> >                 return ret;
> >
> > +       /*
> > +        * The source pad format size comes directly from the sink
> > +        * compose rectangle.
> > +        */
> > +       subdevFormat.size = ispCompose.size();
> >         subdevFormat.code = maliC55FmtToCode.find(config.pixelFormat)->second;
> >         return pipe->resizer->setFormat(1, &subdevFormat);
> >  }
> > --
> > 2.30.2
> >