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

Message ID 1560514294-29111-7-git-send-email-sorganov@gmail.com (mailing list archive)
State RFC
Headers show
Series serial: imx: fix RTS and RTS/CTS handling | expand

Commit Message

Sergey Organov June 14, 2019, 12:11 p.m. UTC 
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@gmail.com>
---
 drivers/tty/serial/imx.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)
diff mbox series

Patch

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);
 	}