tty/serial: omap: empty the RX FIFO at the end of half-duplex TX

Provided that the SER_RS485_RX_DURING_TX flag is not set, empty the
RX FIFO to prevent reading back the transmitted data.
Signed-off-by: NDimitris Lampridis <dlampridis@logikonlabs.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/omap-serial.c

@@ -342,6 +342,12 @@ static void serial_omap_stop_tx(struct uart_port *port)
 
 	if ((up->rs485.flags & SER_RS485_ENABLED) &&
 	    !(up->rs485.flags & SER_RS485_RX_DURING_TX)) {
+		/*
+		 * Empty the RX FIFO, we are not interested in anything
+		 * received during the half-duplex transmission.
+		 */
+		serial_out(up, UART_FCR, up->fcr | UART_FCR_CLEAR_RCVR);
+		/* Re-enable RX interrupts */
 		up->ier |= UART_IER_RLSI | UART_IER_RDI;
 		up->port.read_status_mask |= UART_LSR_DR;
 		serial_out(up, UART_IER, up->ier);