tty/serial: atmel: fix out of range clock divider handling

Use MCK_DIV8 when the clock divider is > 65535. Unfortunately the mode
register was already written thus the clock selection is ignored.

Fix by writing the mode register after calculating the baudrate.

Signed-off-by: David Engraf <david.engraf@sysgo.com>
Link: https://lore.kernel.org/r/20191211162954.8393-1-david.engraf@sysgo.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index a8dc8af..9983e2f 100644 (file)
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -2270,9 +2270,6 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
                mode |= ATMEL_US_USMODE_NORMAL;
        }
 
-       /* set the mode, clock divisor, parity, stop bits and data size */
-       atmel_uart_writel(port, ATMEL_US_MR, mode);
-
        /*
         * when switching the mode, set the RTS line state according to the
         * new mode, otherwise keep the former state
@@ -2315,6 +2312,9 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
        }
        quot = cd | fp << ATMEL_US_FP_OFFSET;
 
+       /* set the mode, clock divisor, parity, stop bits and data size */
+       atmel_uart_writel(port, ATMEL_US_MR, mode);
+
        if (!(port->iso7816.flags & SER_ISO7816_ENABLED))
                atmel_uart_writel(port, ATMEL_US_BRGR, quot);
        atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);