[PATCH v3 06/17] libcamera: converter_v4l2_m2m: Improve crop bounds support

[Stefan Klug]

When a converter (dw100 on imx8mp in this case) is used in a pipeline,
the ScalerCrop control get's created at createCamera() time. As this is
before configure(), no streams were configured on the converter and the
stream specific crop bounds are not known. Extend the converter class to
report the default crop bounds in case the provided stream is not found.

Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
---
 .../internal/converter/converter_v4l2_m2m.h   |   1 +
 src/libcamera/converter.cpp                   |   3 +
 .../converter/converter_v4l2_m2m.cpp          | 113 +++++++++---------
 3 files changed, 59 insertions(+), 58 deletions(-)

diff --git a/include/libcamera/internal/converter/converter_v4l2_m2m.h b/include/libcamera/internal/converter/converter_v4l2_m2m.h
index 0bc0d053e2c4..a5286166f574 100644
--- a/include/libcamera/internal/converter/converter_v4l2_m2m.h
+++ b/include/libcamera/internal/converter/converter_v4l2_m2m.h
@@ -105,6 +105,7 @@ private:
 
 	std::map<const Stream *, std::unique_ptr<V4L2M2MStream>> streams_;
 	std::map<FrameBuffer *, unsigned int> queue_;
+	std::pair<Rectangle, Rectangle> inputCropBounds_;
 };
 
 } /* namespace libcamera */
diff --git a/src/libcamera/converter.cpp b/src/libcamera/converter.cpp
index 3a3f84344c5e..aa16970cd446 100644
--- a/src/libcamera/converter.cpp
+++ b/src/libcamera/converter.cpp
@@ -195,6 +195,9 @@ Converter::~Converter()
  * this function should be called after the \a stream has been configured using
  * configure().
  *
+ * When called with an invalid \a stream, the function returns the default crop
+ * bounds of the converter.
+ *
  * \return A pair containing the minimum and maximum crop bound in that order
  */
 
diff --git a/src/libcamera/converter/converter_v4l2_m2m.cpp b/src/libcamera/converter/converter_v4l2_m2m.cpp
index d63ef2f8028f..bd7e5cce600d 100644
--- a/src/libcamera/converter/converter_v4l2_m2m.cpp
+++ b/src/libcamera/converter/converter_v4l2_m2m.cpp
@@ -30,6 +30,52 @@ namespace libcamera {
 
 LOG_DECLARE_CATEGORY(Converter)
 
+namespace {
+
+int getCropBounds(V4L2VideoDevice *device, Rectangle &minCrop,
+		  Rectangle &maxCrop)
+{
+	Rectangle minC;
+	Rectangle maxC;
+
+	/* Find crop bounds */
+	minC.width = 1;
+	minC.height = 1;
+	maxC.width = UINT_MAX;
+	maxC.height = UINT_MAX;
+
+	int ret = device->setSelection(V4L2_SEL_TGT_CROP, &minC);
+	if (ret) {
+		LOG(Converter, Error)
+			<< "Could not query minimum selection crop: "
+			<< strerror(-ret);
+		return ret;
+	}
+
+	ret = device->getSelection(V4L2_SEL_TGT_CROP_BOUNDS, &maxC);
+	if (ret) {
+		LOG(Converter, Error)
+			<< "Could not query maximum selection crop: "
+			<< strerror(-ret);
+		return ret;
+	}
+
+	/* Reset the crop to its maximum */
+	ret = device->setSelection(V4L2_SEL_TGT_CROP, &maxC);
+	if (ret) {
+		LOG(Converter, Error)
+			<< "Could not reset selection crop: "
+			<< strerror(-ret);
+		return ret;
+	}
+
+	minCrop = minC;
+	maxCrop = maxC;
+	return 0;
+}
+
+} /* namespace */
+
 /* -----------------------------------------------------------------------------
  * V4L2M2MConverter::V4L2M2MStream
  */
@@ -98,41 +144,10 @@ int V4L2M2MConverter::V4L2M2MStream::configure(const StreamConfiguration &inputC
 	outputBufferCount_ = outputCfg.bufferCount;
 
 	if (converter_->features() & Feature::InputCrop) {
-		Rectangle minCrop;
-		Rectangle maxCrop;
-
-		/* Find crop bounds */
-		minCrop.width = 1;
-		minCrop.height = 1;
-		maxCrop.width = UINT_MAX;
-		maxCrop.height = UINT_MAX;
-
-		ret = setInputSelection(V4L2_SEL_TGT_CROP, &minCrop);
-		if (ret) {
-			LOG(Converter, Error)
-				<< "Could not query minimum selection crop: "
-				<< strerror(-ret);
-			return ret;
-		}
-
-		ret = getInputSelection(V4L2_SEL_TGT_CROP_BOUNDS, &maxCrop);
-		if (ret) {
-			LOG(Converter, Error)
-				<< "Could not query maximum selection crop: "
-				<< strerror(-ret);
-			return ret;
-		}
-
-		/* Reset the crop to its maximum */
-		ret = setInputSelection(V4L2_SEL_TGT_CROP, &maxCrop);
-		if (ret) {
-			LOG(Converter, Error)
-				<< "Could not reset selection crop: "
-				<< strerror(-ret);
+		ret = getCropBounds(m2m_->output(), inputCropBounds_.first,
+				    inputCropBounds_.second);
+		if (ret)
 			return ret;
-		}
-
-		inputCropBounds_ = { minCrop, maxCrop };
 	}
 
 	return 0;
@@ -258,27 +273,9 @@ V4L2M2MConverter::V4L2M2MConverter(MediaDevice *media)
 		return;
 	}
 
-	/* Discover Feature::InputCrop */
-	Rectangle maxCrop;
-	maxCrop.width = UINT_MAX;
-	maxCrop.height = UINT_MAX;
-
-	ret = m2m_->output()->setSelection(V4L2_SEL_TGT_CROP, &maxCrop);
-	if (ret)
-		return;
-
-	/*
-	 * Rectangles for cropping targets are defined even if the device
-	 * does not support cropping. Their sizes and positions will be
-	 * fixed in such cases.
-	 *
-	 * Set and inspect a crop equivalent to half of the maximum crop
-	 * returned earlier. Use this to determine whether the crop on
-	 * input is really supported.
-	 */
-	Rectangle halfCrop(maxCrop.size() / 2);
-	ret = m2m_->output()->setSelection(V4L2_SEL_TGT_CROP, &halfCrop);
-	if (!ret && halfCrop != maxCrop) {
+	ret = getCropBounds(m2m_->output(), inputCropBounds_.first,
+			    inputCropBounds_.second);
+	if (!ret && inputCropBounds_.first != inputCropBounds_.second) {
 		features_ |= Feature::InputCrop;
 
 		LOG(Converter, Info)
@@ -477,10 +474,10 @@ std::pair<Rectangle, Rectangle>
 V4L2M2MConverter::inputCropBounds(const Stream *stream)
 {
 	auto iter = streams_.find(stream);
-	if (iter == streams_.end())
-		return {};
+	if (iter != streams_.end())
+		return iter->second->inputCropBounds();
 
-	return iter->second->inputCropBounds();
+	return inputCropBounds_;
 }
 
 /**
-- 
2.43.0