libcamera: camera_sensor: Add support for embedded data

Some sensors support producing and transmitting embedded data over a
stream separate from the image stream. Add support for this feature in
the CameraSensor interface, and implement it for the CameraSensorRaw
class. The CameraSensorLegacy uses the default stub implementation, as
the corresponding kernel drivers don't support embedded data.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

3 files changed, 144 insertions, 0 deletions

diff --git a/include/libcamera/internal/camera_sensor.h b/include/libcamera/internal/camera_sensor.h
index b75cde8d..dc77e74a 100644
--- a/include/libcamera/internal/camera_sensor.h
+++ b/include/libcamera/internal/camera_sensor.h
@@ -62,6 +62,11 @@ public:
 				       Transform transform = Transform::Identity,
 				       V4L2SubdeviceFormat *sensorFormat = nullptr) = 0;
 
+	virtual V4L2Subdevice::Stream imageStream() const;
+	virtual std::optional<V4L2Subdevice::Stream> embeddedDataStream() const;
+	virtual V4L2SubdeviceFormat embeddedDataFormat() const;
+	virtual int setEmbeddedDataEnabled(bool enable);
+
 	virtual const ControlList &properties() const = 0;
 	virtual int sensorInfo(IPACameraSensorInfo *info) const = 0;
 	virtual Transform computeTransform(Orientation *orientation) const = 0;
diff --git a/src/libcamera/sensor/camera_sensor.cpp b/src/libcamera/sensor/camera_sensor.cpp
index 9965aa90..7d5551c9 100644
--- a/src/libcamera/sensor/camera_sensor.cpp
+++ b/src/libcamera/sensor/camera_sensor.cpp
@@ -197,6 +197,73 @@ CameraSensor::~CameraSensor() = default;
  */
 
 /**
+ * \brief Retrieve the image source stream
+ *
+ * Sensors that produce multiple streams do not guarantee that the image stream
+ * is always assigned number 0. This function allows callers to retrieve the
+ * image stream on the sensor's source pad, in order to configure the receiving
+ * side accordingly.
+ *
+ * \return The image source stream
+ */
+V4L2Subdevice::Stream CameraSensor::imageStream() const
+{
+	return { 0, 0 };
+}
+
+/**
+ * \brief Retrieve the embedded data source stream
+ *
+ * Some sensors produce embedded data in a stream separate from the image
+ * stream. This function indicates if the sensor supports this feature by
+ * returning the embedded data stream on the sensor's source pad if available,
+ * or an std::optional<> without a value otheriwse.
+ *
+ * \return The embedded data source stream
+ */
+std::optional<V4L2Subdevice::Stream> CameraSensor::embeddedDataStream() const
+{
+	return {};
+}
+
+/**
+ * \brief Retrieve the format on the embedded data stream
+ *
+ * When an embedded data stream is available, this function returns the
+ * corresponding format on the sensor's source pad. The format may vary with
+ * the image stream format, and should therefore be retrieved after configuring
+ * the image stream.
+ *
+ * If the sensor doesn't support embedded data, this function returns a
+ * default-constructed format.
+ *
+ * \return The format on the embedded data stream
+ */
+V4L2SubdeviceFormat CameraSensor::embeddedDataFormat() const
+{
+	return {};
+}
+
+/**
+ * \brief Enable or disable the embedded data stream
+ * \param[in] enable True to enable the embedded data stream, false to disable it
+ *
+ * For sensors that support embedded data, this function enables or disables
+ * generation of embedded data. Some of such sensors always produce embedded
+ * data, in which case this function return -EISCONN if the caller attempts to
+ * disable embedded data.
+ *
+ * If the sensor doesn't support embedded data, this function returns 0 when \a
+ * enable is false, and -ENOSTR otherwise.
+ *
+ * \return 0 on success, or a negative error code otherwise
+ */
+int CameraSensor::setEmbeddedDataEnabled(bool enable)
+{
+	return enable ? -ENOSTR : 0;
+}
+
+/**
  * \fn CameraSensor::properties()
  * \brief Retrieve the camera sensor properties
  * \return The list of camera sensor properties
diff --git a/src/libcamera/sensor/camera_sensor_raw.cpp b/src/libcamera/sensor/camera_sensor_raw.cpp
index 899f7233..827f53ea 100644
--- a/src/libcamera/sensor/camera_sensor_raw.cpp
+++ b/src/libcamera/sensor/camera_sensor_raw.cpp
@@ -84,6 +84,11 @@ public:
 			       Transform transform = Transform::Identity,
 			       V4L2SubdeviceFormat *sensorFormat = nullptr) override;
 
+	V4L2Subdevice::Stream imageStream() const override;
+	std::optional<V4L2Subdevice::Stream> embeddedDataStream() const override;
+	V4L2SubdeviceFormat embeddedDataFormat() const override;
+	int setEmbeddedDataEnabled(bool enable) override;
+
 	const ControlList &properties() const override { return properties_; }
 	int sensorInfo(IPACameraSensorInfo *info) const override;
 	Transform computeTransform(Orientation *orientation) const override;
@@ -878,6 +883,73 @@ int CameraSensorRaw::applyConfiguration(const SensorConfiguration &config,
 	return 0;
 }
 
+V4L2Subdevice::Stream CameraSensorRaw::imageStream() const
+{
+	return streams_.image.source;
+}
+
+std::optional<V4L2Subdevice::Stream> CameraSensorRaw::embeddedDataStream() const
+{
+	if (!streams_.edata)
+		return {};
+
+	return { streams_.edata->source };
+}
+
+V4L2SubdeviceFormat CameraSensorRaw::embeddedDataFormat() const
+{
+	if (!streams_.edata)
+		return {};
+
+	V4L2SubdeviceFormat format;
+	int ret = subdev_->getFormat(streams_.edata->source, &format);
+	if (ret)
+		return {};
+
+	return format;
+}
+
+int CameraSensorRaw::setEmbeddedDataEnabled(bool enable)
+{
+	if (!streams_.edata)
+		return enable ? -ENOSTR : 0;
+
+	V4L2Subdevice::Routing routing{ 2 };
+
+	routing[0].sink = streams_.image.sink;
+	routing[0].source = streams_.image.source;
+	routing[0].flags = V4L2_SUBDEV_ROUTE_FL_ACTIVE;
+
+	routing[1].sink = streams_.edata->sink;
+	routing[1].source = streams_.edata->source;
+	routing[1].flags = enable ? V4L2_SUBDEV_ROUTE_FL_ACTIVE : 0;
+
+	int ret = subdev_->setRouting(&routing);
+	if (ret)
+		return ret;
+
+	/*
+	 * Check if the embedded data stream has been enabled or disabled
+	 * correctly. Assume at least one route will match the embedded data
+	 * source stream, as there would be something seriously wrong
+	 * otherwise.
+	 */
+	bool enabled = false;
+
+	for (const V4L2Subdevice::Route &route : routing) {
+		if (route.source != streams_.edata->source)
+			continue;
+
+		enabled = route.flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE;
+		break;
+	}
+
+	if (enabled != enable)
+		return enabled ? -EISCONN : -ENOSTR;
+
+	return 0;
+}
+
 int CameraSensorRaw::sensorInfo(IPACameraSensorInfo *info) const
 {
 	info->model = model();