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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Fabio Estevam <fabio.estevam@nxp.com>,
        Martin Kaiser <martin@kaiser.cx>,
        Fugang Duan <fugang.duan@nxp.com>
Subject: [PATCH 4.15 48/55] serial: imx: Only wakeup via RTSDEN bit if the system has RTS/CTS
Date:   Fri,  2 Feb 2018 17:59:06 +0100
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4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Fabio Estevam <fabio.estevam@nxp.com>

commit 38b1f0fb42f772b8c9aac53593883a18ff5eb9d7 upstream.

The wakeup mechanism via RTSDEN bit relies on the system using the RTS/CTS
lines, so only allow such wakeup method when the system actually has
RTS/CTS support.

Fixes: bc85734b126f ("serial: imx: allow waking up on RTSD")
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Martin Kaiser <martin@kaiser.cx>
Acked-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/tty/serial/imx.c |   14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2238,12 +2238,14 @@ static void serial_imx_enable_wakeup(str
 		val &= ~UCR3_AWAKEN;
 	writel(val, sport->port.membase + UCR3);
 
-	val = readl(sport->port.membase + UCR1);
-	if (on)
-		val |= UCR1_RTSDEN;
-	else
-		val &= ~UCR1_RTSDEN;
-	writel(val, sport->port.membase + UCR1);
+	if (sport->have_rtscts) {
+		val = readl(sport->port.membase + UCR1);
+		if (on)
+			val |= UCR1_RTSDEN;
+		else
+			val &= ~UCR1_RTSDEN;
+		writel(val, sport->port.membase + UCR1);
+	}
 }
 
 static int imx_serial_port_suspend_noirq(struct device *dev)