libcamera: Document missing parameters and return values

Several functions are missing documentation for some of them parameters
and/or for their return value. Fix this.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/device_enumerator.cpp

@@ -124,6 +124,9 @@ bool DeviceMatch::match(const MediaDevice *device) const
  * implementations may be needed. This function creates the best enumerator for
  * the operating system based on the available resources. Not all different
  * enumerator types are guaranteed to support all features.
+ *
+ * \return A pointer to the newly created device enumerator on success, or
+ * nullptr if an error occurs
  */
 DeviceEnumerator *DeviceEnumerator::create()
 {

src/libcamera/log.cpp

@@ -90,6 +90,11 @@ static const char *log_severity_name(LogSeverity severity)
  */
 
 /**
+ * \param fileName The file name where the message is logged from
+ * \param line The line number where the message is logged from
+ * \param severity The log message severity, controlling how the message will be
+ * displayed
+ *
  * Create a log message pertaining to line \a line of file \a fileName. The
  * \a severity argument sets the message severity to control whether it will be
  * output or dropped.
@@ -130,6 +135,8 @@ LogMessage::~LogMessage()
  * Data is added to a LogMessage through the stream returned by this function.
  * The stream implements the std::ostream API and can be used for logging as
  * std::cout.
+ *
+ * \return A reference to the log message stream
  */
 
 } /* namespace libcamera */

src/libcamera/pipeline_handler.cpp

@@ -36,11 +36,13 @@ namespace libcamera {
 /**
  * \fn PipelineHandler::match(DeviceEnumerator *enumerator)
  * \brief Match media devices and create camera instances
+ * \param enumerator The enumerator providing all media devices found in the
+ * system
  *
  * This function is the main entry point of the pipeline handler. It is called
- * by the device enumerator with the enumerator passed as an argument. It shall
- * acquire from the enumerator all the media devices it needs for a single
- * pipeline and create one or multiple Camera instances.
+ * by the device enumerator with the \a enumerator passed as an argument. It
+ * shall acquire from the \a enumerator all the media devices it needs for a
+ * single pipeline and create one or multiple Camera instances.
  *
  * If all media devices needed by the pipeline handler are found, they must all
  * be acquired by a call to MediaDevice::acquire(). This function shall then

src/libcamera/signal.cpp

@@ -58,21 +58,26 @@ namespace libcamera {
 /**
  * \fn Signal::disconnect(T *object)
  * \brief Disconnect the signal from all slots of the \a object
+ * \param object The object pointer whose slots to disconnect
  */
 
 /**
  * \fn Signal::disconnect(T *object, void(T::*func)(Args...))
  * \brief Disconnect the signal from the \a object slot member function \a func
+ * \param object The object pointer whose slots to disconnect
+ * \param func The slot member function to disconnect
  */
 
 /**
  * \fn Signal::disconnect(void(*func)(Args...))
  * \brief Disconnect the signal from the slot static function \a func
+ * \param func The slot static function to disconnect
  */
 
 /**
  * \fn Signal::emit(Args... args)
  * \brief Emit the signal and call all connected slots
+ * \param args The arguments passed to the connected slots
  *
  * Emitting a signal calls all connected slots synchronously and sequentially in
  * the order the slots have been connected. The arguments passed to the emit()