serial: imx: set_termios(): preserve RTS state

imx_set_termios() cleared RTS on every call, now fixed.

Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Tested-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1561558293-7683-5-git-send-email-sorganov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 5 deletions

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 1cb891b4eaa0..57d6e6ba556e 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1562,7 +1562,14 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
 
         spin_lock_irqsave(&sport->port.lock, flags);
 
-        ucr2 = UCR2_SRST | UCR2_IRTS;
+        /*
+         * Read current UCR2 and save it for future use, then clear all the bits
+         * except those we will or may need to preserve.
+         */
+        old_ucr2 = imx_uart_readl(sport, UCR2);
+        ucr2 = old_ucr2 & (UCR2_TXEN | UCR2_RXEN | UCR2_ATEN | UCR2_CTS);
+
+        ucr2 |= UCR2_SRST | UCR2_IRTS;
         if ((termios->c_cflag & CSIZE) == CS8)
                 ucr2 |= UCR2_WS;
 
@@ -1631,7 +1638,6 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
         imx_uart_writel(sport,
                         old_ucr1 & ~(UCR1_TXMPTYEN | UCR1_RRDYEN | UCR1_RTSDEN),
                         UCR1);
-        old_ucr2 = imx_uart_readl(sport, UCR2);
         imx_uart_writel(sport, old_ucr2 & ~UCR2_ATEN, UCR2);
 
         while (!(imx_uart_readl(sport, USR2) & USR2_TXDC))
@@ -1639,7 +1645,6 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
 
         /* then, disable everything */
         imx_uart_writel(sport, old_ucr2 & ~(UCR2_TXEN | UCR2_RXEN | UCR2_ATEN), UCR2);
-        old_ucr2 &= (UCR2_TXEN | UCR2_RXEN | UCR2_ATEN);
 
         /* custom-baudrate handling */
         div = sport->port.uartclk / (baud * 16);
@@ -1677,8 +1682,7 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
 
         imx_uart_writel(sport, old_ucr1, UCR1);
 
-        /* set the parity, stop bits and data size */
-        imx_uart_writel(sport, ucr2 | old_ucr2, UCR2);
+        imx_uart_writel(sport, ucr2, UCR2);
 
         if (UART_ENABLE_MS(&sport->port, termios->c_cflag))
                 imx_uart_enable_ms(&sport->port);