tty: serial: fsl_lpuart: clear LPUART Status Register in lpuart32_shutdown()

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@nxp.com>
Link: https://lore.kernel.org/r/20221125101953.18753-4-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 88697ddcd8c4ff608d9dfd677a4fff70cac8927f..8918e08bb19eef5f8263ce9ced6bf39e464bd56a 100644 (file)
--- 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);