linux-kernel - [PATCH v2 15/22] usb: serial: ti_usb_3410_5052: Check old_termios parameter in set

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Date:	Tue, 26 Jul 2016 19:59:55 +0200
From:	Mathieu OTHACEHE <m.othacehe@...il.com>
To:	johan@...nel.org, gregkh@...uxfoundation.org
Cc:	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	Mathieu OTHACEHE <m.othacehe@...il.com>
Subject: [PATCH v2 15/22] usb: serial: ti_usb_3410_5052: Check old_termios parameter in set_termios

The old_termios parameter is never used in set_termios callback.

Add a check to old_termios to see if we can return right away because
there is nothing to change.

Also pass NULL for old_termios in open callback because it is the
initial call to set_termios.

Signed-off-by: Mathieu OTHACEHE <m.othacehe@...il.com>
---
Changelog:
v2:
* Deal with DTR and RTS raising in the next patch.

 drivers/usb/serial/ti_usb_3410_5052.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/serial/ti_usb_3410_5052.c b/drivers/usb/serial/ti_usb_3410_5052.c
index b5ea850..d488237 100644
--- a/drivers/usb/serial/ti_usb_3410_5052.c
+++ b/drivers/usb/serial/ti_usb_3410_5052.c
@@ -740,7 +740,7 @@ static int ti_open(struct tty_struct *tty, struct usb_serial_port *port)
 	}
 
 	if (tty)
-		ti_set_termios(tty, port, &tty->termios);
+		ti_set_termios(tty, port, NULL);
 
 	status = ti_send_ctrl_urb(serial, TI_OPEN_PORT, open_settings,
 				  TI_UART1_PORT + port_number);
@@ -780,7 +780,7 @@ static int ti_open(struct tty_struct *tty, struct usb_serial_port *port)
 	usb_clear_halt(dev, port->read_urb->pipe);
 
 	if (tty)
-		ti_set_termios(tty, port, &tty->termios);
+		ti_set_termios(tty, port, NULL);
 
 	status = ti_send_ctrl_urb(serial, TI_OPEN_PORT, open_settings,
 				  TI_UART1_PORT + port_number);
@@ -993,6 +993,13 @@ static void ti_set_termios(struct tty_struct *tty,
 	cflag = tty->termios.c_cflag;
 	iflag = tty->termios.c_iflag;
 
+	if (old_termios &&
+		!tty_termios_hw_change(&tty->termios, old_termios) &&
+		tty->termios.c_iflag == old_termios->c_iflag) {
+		dev_dbg(&port->dev, "%s - nothing to change\n", __func__);
+		return;
+	}
+
 	dev_dbg(&port->dev,
 		"%s - cflag 0x%08x, iflag 0x%08x\n", __func__, cflag, iflag);
 
-- 
2.9.0