serial: samsung: Reorder the sequence of clock control when call s3c24xx_serial_set_t...

[ Upstream commit b8995f527aac143e83d3900ff39357651ea4e0f6 ]

This patch fixes the broken serial log when changing the clock source
of uart device. Before disabling the original clock source, this patch
enables the new clock source to protect the clock off state for a split second.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 587d63bcbd0e0490021231c349061a7dbc4ba157..b7213637f4989588cf1b85abcad9dbdfce544609 100644 (file)
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -749,6 +749,8 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
        /* check to see if we need  to change clock source */
 
        if (ourport->baudclk != clk) {
+               clk_prepare_enable(clk);
+
                s3c24xx_serial_setsource(port, clk_sel);
 
                if (!IS_ERR(ourport->baudclk)) {
@@ -756,8 +758,6 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
                        ourport->baudclk = ERR_PTR(-EINVAL);
                }
 
-               clk_prepare_enable(clk);
-
                ourport->baudclk = clk;
                ourport->baudclk_rate = clk ? clk_get_rate(clk) : 0;
        }