[PATCH RFC 6/7] serial: imx: set_mctrl(): correctly restore autoRTS state

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imx_uart_set_mctrl() happened to set UCR2_CTSC bit whenever TIOCM_RTS
was set, no matter if RTS/CTS handshake is enabled or not. Now fixed by
turning handshake on only when CRTSCTS bit for the port is set.

Signed-off-by: Sergey Organov <sorganov@xxxxxxxxx>
---
 drivers/tty/serial/imx.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index de23068..bdb8b6a 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -970,10 +970,19 @@ static void imx_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 	if (!(port->rs485.flags & SER_RS485_ENABLED)) {
 		u32 ucr2;
 
+		/*
+		 * Turn off autoRTS (UCR2_CTSC) if RTS is lowered and restore
+		 * autoRTS setting if RTS is raised. Inverted UCR2_IRTS is set
+		 * if and only if CRTSCTS bit is set for the port, so we use it
+		 * to get the state to restore to.
+		 */
 		ucr2 = imx_uart_readl(sport, UCR2);
 		ucr2 &= ~(UCR2_CTS | UCR2_CTSC);
-		if (mctrl & TIOCM_RTS)
-			ucr2 |= UCR2_CTS | UCR2_CTSC;
+		if (mctrl & TIOCM_RTS) {
+			ucr2 |= UCR2_CTS;
+			if (!(ucr2 & UCR2_IRTS))
+				ucr2 |= UCR2_CTSC;
+		}
 		imx_uart_writel(sport, ucr2, UCR2);
 	}
 
-- 
2.10.0.1.g57b01a3




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