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: Dimitris Lampridis <dlampridis@logikonlabs.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 65abea2c6e47..dd8b1a5458ff 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/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);