libcamera: converter: Add interface for feature flags

This patch intends to extend the converter interface to have feature
flags, which enables each converter to expose the set of features
it supports.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

include/libcamera/internal/converter.h

@@ -17,6 +17,7 @@
 #include <vector>
 
 #include <libcamera/base/class.h>
+#include <libcamera/base/flags.h>
 #include <libcamera/base/signal.h>
 
 #include <libcamera/geometry.h>
@@ -32,7 +33,13 @@ struct StreamConfiguration;
 class Converter
 {
 public:
-	Converter(MediaDevice *media);
+	enum class Feature {
+		None = 0,
+	};
+
+	using Features = Flags<Feature>;
+
+	Converter(MediaDevice *media, Features features = Feature::None);
 	virtual ~Converter();
 
 	virtual int loadConfiguration(const std::string &filename) = 0;
@@ -61,6 +68,11 @@ public:
 
 	const std::string &deviceNode() const { return deviceNode_; }
 
+	Features features() const { return features_; }
+
+protected:
+	Features features_;
+
 private:
 	std::string deviceNode_;
 };

src/libcamera/converter.cpp

@@ -34,14 +34,27 @@ LOG_DEFINE_CATEGORY(Converter)
  * parameters from the same input stream.
  */
 
+/**
+ * \enum Converter::Feature
+ * \brief Specify the features supported by the converter
+ * \var Converter::Feature::None
+ * \brief No extra features supported by the converter
+ */
+
+/**
+ * \typedef Converter::Features
+ * \brief A bitwise combination of features supported by the converter
+ */
+
 /**
  * \brief Construct a Converter instance
  * \param[in] media The media device implementing the converter
+ * \param[in] features Features flags representing supported features
  *
  * This searches for the entity implementing the data streaming function in the
  * media graph entities and use its device node as the converter device node.
  */
-Converter::Converter(MediaDevice *media)
+Converter::Converter(MediaDevice *media, Features features)
 {
 	const std::vector<MediaEntity *> &entities = media->entities();
 	auto it = std::find_if(entities.begin(), entities.end(),
@@ -56,6 +69,7 @@ Converter::Converter(MediaDevice *media)
 	}
 
 	deviceNode_ = (*it)->deviceNode();
+	features_ = features;
 }
 
 Converter::~Converter()
@@ -157,12 +171,23 @@ Converter::~Converter()
  * \brief A signal emitted on each frame buffer completion of the output queue
  */
 
+/**
+ * \var Converter::features_
+ * \brief Stores the features supported by the converter
+ */
+
 /**
  * \fn Converter::deviceNode()
  * \brief The converter device node attribute accessor
  * \return The converter device node string
  */
 
+/**
+ * \fn Converter::features()
+ * \brief Retrieve the features supported by the converter
+ * \return The converter Features flags
+ */
+
 /**
  * \class ConverterFactoryBase
  * \brief Base class for converter factories

src/libcamera/converter/converter_v4l2_m2m.cpp

@@ -446,6 +446,10 @@ int V4L2M2MConverter::queueBuffers(FrameBuffer *input,
 	return 0;
 }
 
+/*
+ * \todo: This should be extended to include Feature::Flag to denote
+ * what each converter supports feature-wise.
+ */
 static std::initializer_list<std::string> compatibles = {
 	"mtk-mdp",
 	"pxp",