Implemented flush for Serial UART API

platforms/common/Serial.cpp

@@ -80,6 +80,11 @@ ssize_t Serial::write(const void *buffer, size_t buffer_size)
 	return _impl.write(buffer, buffer_size);
 }
 
+void Serial::flush()
+{
+	return _impl.flush();
+}
+
 uint32_t Serial::getBaudrate() const
 {
 	return _impl.getBaudrate();

platforms/common/include/px4_platform_common/Serial.hpp

@@ -64,6 +64,8 @@ public:
 
 	ssize_t write(const void *buffer, size_t buffer_size);
 
+	void flush();
+
 	// If port is already open then the following configuration functions
 	// will reconfigure the port. If the port is not yet open then they will
 	// simply store the configuration in preparation for the port to be opened.

platforms/nuttx/src/px4/common/SerialImpl.cpp

@@ -309,6 +309,13 @@ ssize_t SerialImpl::write(const void *buffer, size_t buffer_size)
 	return written;
 }
 
+void SerialImpl::flush()
+{
+	if (_open) {
+		tcflush(_serial_fd, TCIOFLUSH);
+	}
+}
+
 const char *SerialImpl::getPort() const
 {
 	return _port;

platforms/nuttx/src/px4/common/include/SerialImpl.hpp

@@ -64,6 +64,8 @@ public:
 
 	ssize_t write(const void *buffer, size_t buffer_size);
 
+	void flush();
+
 	const char *getPort() const;
 
 	uint32_t getBaudrate() const;

platforms/posix/include/SerialImpl.hpp

@@ -64,6 +64,8 @@ public:
 
 	ssize_t write(const void *buffer, size_t buffer_size);
 
+	void flush();
+
 	const char *getPort() const;
 
 	uint32_t getBaudrate() const;

platforms/posix/src/px4/common/SerialImpl.cpp

@@ -309,6 +309,13 @@ ssize_t SerialImpl::write(const void *buffer, size_t buffer_size)
 	return written;
 }
 
+void SerialImpl::flush()
+{
+	if (_open) {
+		tcflush(_serial_fd, TCIOFLUSH);
+	}
+}
+
 const char *SerialImpl::getPort() const
 {
 	return _port;

platforms/qurt/include/SerialImpl.hpp

@@ -63,6 +63,8 @@ public:
 
 	ssize_t write(const void *buffer, size_t buffer_size);
 
+	void flush();
+
 	const char *getPort() const;
 	bool setPort(const char *port);
 

platforms/qurt/src/px4/SerialImpl.cpp

@@ -251,6 +251,15 @@ ssize_t SerialImpl::write(const void *buffer, size_t buffer_size)
 	return ret_write;
 }
 
+void SerialImpl::flush()
+{
+	if (_open) {
+		uint8_t buffer[4];
+		// A read clears out all current data
+		read(buffer, 4);
+	}
+}
+
 const char *SerialImpl::getPort() const
 {
 	return _port;

src/drivers/rc/crsf_rc/CrsfRc.cpp

@@ -116,11 +116,13 @@ void CrsfRc::Run()
 {
 	if (should_exit()) {
 		ScheduleClear();
+
 		if (_uart) {
 			(void) _uart->close();
 			delete _uart;
 			_uart = nullptr;
 		}
+
 		exit_and_cleanup();
 		return;
 	}
@@ -152,26 +154,26 @@ void CrsfRc::Run()
 			return;
 		}
 
-// 			if (board_rc_swap_rxtx(_device)) {
-// #if defined(TIOCSSWAP)
-// 				ioctl(_rc_fd, TIOCSSWAP, SER_SWAP_ENABLED);
-// #endif // TIOCSSWAP
-// 			}
-// 
-// 			if (board_rc_singlewire(_device)) {
-// 				_is_singlewire = true;
-// #if defined(TIOCSSINGLEWIRE)
-// 				ioctl(_rc_fd, TIOCSSINGLEWIRE, SER_SINGLEWIRE_ENABLED);
-// #endif // TIOCSSINGLEWIRE
-// 			}
-// 
-// 			PX4_INFO("Crsf serial opened sucessfully");
-// 
-// 			if (_is_singlewire) {
-// 				PX4_INFO("Crsf serial is single wire. Telemetry disabled");
-// 			}
-// 
-// 			tcflush(_rc_fd, TCIOFLUSH);
+		if (board_rc_swap_rxtx(_device)) {
+#if defined(TIOCSSWAP)
+			ioctl(_rc_fd, TIOCSSWAP, SER_SWAP_ENABLED);
+#endif // TIOCSSWAP
+		}
+
+		if (board_rc_singlewire(_device)) {
+			_is_singlewire = true;
+#if defined(TIOCSSINGLEWIRE)
+			ioctl(_rc_fd, TIOCSSINGLEWIRE, SER_SINGLEWIRE_ENABLED);
+#endif // TIOCSSINGLEWIRE
+		}
+
+		PX4_INFO("Crsf serial opened sucessfully");
+
+		if (_is_singlewire) {
+			PX4_INFO("Crsf serial is single wire. Telemetry disabled");
+		}
+
+		_uart->flush();
 
 		Crc8Init(0xd5);