linux-kernel - [PATCH V2 5/5] tty: serial: fsl_lpuart: clear LPUART Status Register in lpuart32

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Message-Id: <20221110081728.10172-6-sherry.sun@nxp.com>
Date:   Thu, 10 Nov 2022 16:17:28 +0800
From:   Sherry Sun <sherry.sun@....com>
To:     gregkh@...uxfoundation.org, jirislaby@...nel.org
Cc:     michael@...le.cc, jingchang.lu@...escale.com,
        tomonori.sakita@...d.co.jp, atsushi.nemoto@...d.co.jp,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-imx@....com
Subject: [PATCH V2 5/5] 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@....com>
---
Changes in V2:
1. Split one patch into four smaller patches to improve the commit
messages and add Fixes tag as suggested by Ilpo.
---
 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 c297be11422a..75162c4784dd 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1769,6 +1769,10 @@ static void lpuart32_shutdown(struct uart_port *port)
 
 	spin_lock_irqsave(&port->lock, flags);
 
+	/* clear statue */
+	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