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>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 7d3a3f5cb5babfaec4126ab5f7be9fe740de9068..0a70d12fe33c6553c4e9168be7fe90114ed813ab 100644 (file)
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -734,6 +734,8 @@ 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)) {
@@ -741,8 +743,6 @@ 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;
        }