[PATCH v2] serial: imx: protect Soft Reset of port with lock

[Jiada Wang]

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@xxxxxxxxxx>
---
 drivers/tty/serial/imx.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index c8cfa06..38717c7 100644
--- 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
 	 */
-- 
1.9.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/