[PATCH v4 12/13] libcamera: mali-c55: Enable usage of scaler

[Kieran Bingham]

Quoting Daniel Scally (2024-07-09 15:39:12)
> 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.
> 
> Reviewed-by: Daniel Scally <dan.scally at ideasonboard.com>
> Signed-off-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
> Signed-off-by: Daniel Scally <dan.scally at ideasonboard.com>
> ---
>  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 512a7489..f5ca2ca4 100644
> --- a/src/libcamera/pipeline/mali-c55/mali-c55.cpp
> +++ b/src/libcamera/pipeline/mali-c55/mali-c55.cpp
> @@ -747,16 +747,28 @@ 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;

Seeing open-coding for centering makes me think we're missing some
helper in geometry.h ... but it looks correct.

> +       Rectangle ispCrop = { xCrop, yCrop, scalerIn };

I think we should be reporting this as ScalerCrop in the metadata to
tell applications exactly what region they are getting from the Sensor.

Of course implementing ScalerCrop as a control will be good to come
later too ;-)

Do we have a request/metadata we can access here in this function to
report this already?

If not - I think we can deal with it when ScalerCrop is actually
implemented anyway.

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

>         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);
>  }
> -- 
> 2.34.1
>