From df8ad62006f452ee4902e216e955f1a142cf144f Mon Sep 17 00:00:00 2001 From: Chanwoo Choi Date: Thu, 21 Apr 2016 18:58:31 +0900 Subject: [PATCH 1/1] serial: samsung: Reorder the sequence of clock control when call s3c24xx_serial_set_termios() 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 Reviewed-by: Marek Szyprowski Signed-off-by: Greg Kroah-Hartman Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Krzysztof Kozlowski --- drivers/tty/serial/samsung.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c index d72cd736bdc6..8320173af846 100644 --- a/drivers/tty/serial/samsung.c +++ b/drivers/tty/serial/samsung.c @@ -1263,6 +1263,8 @@ 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)) { @@ -1270,8 +1272,6 @@ 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; } -- 2.11.0