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

[ Upstream commit 4029dfc034febb54f6dd8ea83568accc943bc088 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 262b059e3ee1161f179a29d5202723a3d5f915c7..110c8720af47a6c37d8f9b2528956f1e97bbd4cb 100644 (file)
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1791,6 +1791,10 @@ 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);