[PATCH V3 3/3] tty: serial: fsl_lpuart: clear LPUART Status Register in lpuart32_shutdown()

[Sherry Sun]

The LPUART Status Register needs to be cleared when closing the uart
port to get a clean environment when reopening the uart.

Fixes: 380c966c093e ("tty: serial: fsl_lpuart: add 32-bit register interface support")
Signed-off-by: Sherry Sun <sherry.sun@xxxxxxx>
---
 drivers/tty/serial/fsl_lpuart.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 88697ddcd8c4..8918e08bb19e 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1799,6 +1799,10 @@ static void lpuart32_shutdown(struct uart_port *port)
 
 	spin_lock_irqsave(&port->lock, flags);
 
+	/* clear status */
+	temp = lpuart32_read(&sport->port, UARTSTAT);
+	lpuart32_write(&sport->port, temp, UARTSTAT);
+
 	/* disable Rx/Tx DMA */
 	temp = lpuart32_read(port, UARTBAUD);
 	temp &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE);
-- 
2.17.1