serial: imx: protect Soft Reset of port with lock

Previously Soft Reset (clear of SRST bit in UCR2 register)
of UART in startup is not protected by lock, which may have race
with console_write, as console_write may occur at anytime even
when UART port is shutdown.

To avoid this race, protect Soft reset of UART port with spin_lock.

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index c8cfa06371280af6abfd63bd379ee5c121523ad7..38717c7bb46f31e74ba0e7673feaabfef7091c8f 100644 (file)
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1114,6 +1114,12 @@ static int imx_startup(struct uart_port *port)
 
        writel(temp & ~UCR4_DREN, sport->port.membase + UCR4);
 
+       /* Can we enable the DMA support? */
+       if (is_imx6q_uart(sport) && !uart_console(port) &&
+           !sport->dma_is_inited)
+               imx_uart_dma_init(sport);
+
+       spin_lock_irqsave(&sport->port.lock, flags);
        /* Reset fifo's and state machines */
        i = 100;
 
@@ -1124,13 +1130,6 @@ static int imx_startup(struct uart_port *port)
        while (!(readl(sport->port.membase + UCR2) & UCR2_SRST) && (--i > 0))
                udelay(1);
 
-       /* Can we enable the DMA support? */
-       if (is_imx6q_uart(sport) && !uart_console(port) &&
-           !sport->dma_is_inited)
-               imx_uart_dma_init(sport);
-
-       spin_lock_irqsave(&sport->port.lock, flags);
-
        /*
         * Finally, clear and enable interrupts
         */