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

[Daniel Scally]

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>
---
 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 };
 	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