serial: samsung: move clock deactivation below uart registration

Commit 60e93575476f (serial: samsung: enable clock before clearing pending
interrupts during init) added handling of the controller clock during init.

On most systems this clock is also one of the baud_clock sources and
possibly used by the earlycon and thus already enabled by the bootloader.

Therefore a gap exists between s3c24xx_serial_init_port disabling the
clock and an attached console reenabling it, making the transition from
earlycon to regular console possibly hang the system - as seen on my
S3C2442 based Freerunner today.

Therefore move the disabling of the clock from s3c24xx_serial_init_port
below the uart port registration, effectively creating an overlap and
keeping the clock running non-stop if the console wants to grab this port.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index c1af04d46682..9cd706df3b33 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -1209,7 +1209,6 @@ static int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport,
 
         /* reset the fifos (and setup the uart) */
         s3c24xx_serial_resetport(port, cfg);
-        clk_disable_unprepare(ourport->clk);
         return 0;
 }
 
@@ -1287,6 +1286,13 @@ static int s3c24xx_serial_probe(struct platform_device *pdev)
         uart_add_one_port(&s3c24xx_uart_drv, &ourport->port);
         platform_set_drvdata(pdev, &ourport->port);
 
+        /*
+         * Deactivate the clock enabled in s3c24xx_serial_init_port here,
+         * so that a potential re-enablement through the pm-callback overlaps
+         * and keeps the clock enabled in this case.
+         */
+        clk_disable_unprepare(ourport->clk);
+
 #ifdef CONFIG_SAMSUNG_CLOCK
         ret = device_create_file(&pdev->dev, &dev_attr_clock_source);
         if (ret < 0)