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

commit b8995f527aac143e83d3900ff39357651ea4e0f6 upstream.

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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 91f29f2975c185b7401482d6c9b4a7676e5920bc..5d1bfbe14f276e8cb1f32b0a0284e375e3bac85f 100644 (file)
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -757,6 +757,8 @@ 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)) {
@@ -764,8 +766,6 @@ 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;
        }