linux-kernel - [PATCH 1/1] serial: fsl_lpuart: RS485 RTS polariy is inverse

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Message-Id: <20220802163854.1055323-1-shenwei.wang@nxp.com>
Date:   Tue,  2 Aug 2022 11:38:54 -0500
From:   Shenwei Wang <shenwei.wang@....com>
To:     gregkh@...uxfoundation.org, jirislaby@...nel.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        NXP Linux Team <linux-imx@....com>,
        Shenwei Wang <shenwei.wang@....com>,
        Nicolas Diaz <nicolas.diaz@....com>
Subject: [PATCH 1/1] serial: fsl_lpuart: RS485 RTS polariy is inverse

The setting of RS485 RTS polarity is inverse in the current driver.

When the property of 'rs485-rts-active-low' is enabled in the dts node,
the RTS signal should be LOW during sending. Otherwise, if there is no
such a property, the RTS should be HIGH during sending.

Signed-off-by: Nicolas Diaz <nicolas.diaz@....com>
Signed-off-by: Shenwei Wang <shenwei.wang@....com>
---
 drivers/tty/serial/fsl_lpuart.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index afa0f941c862f..abc3a3674bc39 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1394,9 +1394,9 @@ static int lpuart_config_rs485(struct uart_port *port, struct ktermios *termios,
 		 * Note: UART is assumed to be active high.
 		 */
 		if (rs485->flags & SER_RS485_RTS_ON_SEND)
-			modem &= ~UARTMODEM_TXRTSPOL;
-		else if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
 			modem |= UARTMODEM_TXRTSPOL;
+		else if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
+			modem &= ~UARTMODEM_TXRTSPOL;
 	}
 
 	writeb(modem, sport->port.membase + UARTMODEM);
-- 
2.25.1