[PATCH v4 7/7] serial: rsci: Simplify rsci_transmit_chars()

[Diogo Ivo <diogo.ivo.sx@renesas.com>]

Now that sci_er_interrupt() no longer calls sci_tx_interrupt() on RSCI
ports, rsci_transmit_chars() is only invoked when CSR.TDRE and CCR0.TE
are set.

Drop the redundant CCR0.TIE manipulation in the !CSR_TDRE guard and
call rsci_stop_tx() instead of open-coding the CCR0.TIE/CCR0.TEIE
update when transmission stops.

Signed-off-by: Diogo Ivo <diogo.ivo.sx@renesas.com>
---
 drivers/tty/serial/rsci.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/drivers/tty/serial/rsci.c b/drivers/tty/serial/rsci.c
index 05703bb31afd..80087be11808 100644
--- a/drivers/tty/serial/rsci.c
+++ b/drivers/tty/serial/rsci.c
@@ -432,19 +432,12 @@ static void rsci_transmit_chars(struct uart_port *port)
 {
 	unsigned int stopped = uart_tx_stopped(port);
 	struct tty_port *tport = &port->state->port;
-	u32 status, ctrl;
+	u32 status;
 	int count;
 
 	status = rsci_serial_in(port, CSR);
-	if (!(status & CSR_TDRE)) {
-		ctrl = rsci_serial_in(port, CCR0);
-		if (kfifo_is_empty(&tport->xmit_fifo))
-			ctrl &= ~CCR0_TIE;
-		else
-			ctrl |= CCR0_TIE;
-		rsci_serial_out(port, CCR0, ctrl);
+	if (!(status & CSR_TDRE))
 		return;
-	}
 
 	count = rsci_txroom(port);
 
@@ -467,12 +460,8 @@ static void rsci_transmit_chars(struct uart_port *port)
 	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (kfifo_is_empty(&tport->xmit_fifo) || stopped) {
-		ctrl = rsci_serial_in(port, CCR0);
-		ctrl &= ~CCR0_TIE;
-		ctrl |= CCR0_TEIE;
-		rsci_serial_out(port, CCR0, ctrl);
-	}
+	if (kfifo_is_empty(&tport->xmit_fifo) || stopped)
+		rsci_stop_tx(port);
 }
 
 static void rsci_receive_chars(struct uart_port *port)

-- 
2.56.0