patch "USB: serial: ch341: fix modem-control and B0 handling" added to usb-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    USB: serial: ch341: fix modem-control and B0 handling

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 030ee7ae52a46a2be52ccc8242c4a330aba8d38e Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Fri, 6 Jan 2017 19:15:12 +0100
Subject: USB: serial: ch341: fix modem-control and B0 handling

The modem-control signals are managed by the tty-layer during open and
should not be asserted prematurely when set_termios is called from
driver open.

Also make sure that the signals are asserted only when changing speed
from B0.

Fixes: 664d5df92e88 ("USB: usb-serial ch341: support for DTR/RTS/CTS")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/ch341.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 6279df905c14..0cc5056b304d 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -384,10 +384,6 @@ static void ch341_set_termios(struct tty_struct *tty,
 		ctrl |= CH341_LCR_STOP_BITS_2;
 
 	if (baud_rate) {
-		spin_lock_irqsave(&priv->lock, flags);
-		priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
-		spin_unlock_irqrestore(&priv->lock, flags);
-
 		priv->baud_rate = baud_rate;
 
 		r = ch341_init_set_baudrate(port->serial->dev, priv, ctrl);
@@ -395,14 +391,16 @@ static void ch341_set_termios(struct tty_struct *tty,
 			priv->baud_rate = tty_termios_baud_rate(old_termios);
 			tty_termios_copy_hw(&tty->termios, old_termios);
 		}
-	} else {
-		spin_lock_irqsave(&priv->lock, flags);
-		priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
-		spin_unlock_irqrestore(&priv->lock, flags);
 	}
 
-	ch341_set_handshake(port->serial->dev, priv->line_control);
+	spin_lock_irqsave(&priv->lock, flags);
+	if (C_BAUD(tty) == B0)
+		priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
+	else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
+		priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
+	spin_unlock_irqrestore(&priv->lock, flags);
 
+	ch341_set_handshake(port->serial->dev, priv->line_control);
 }
 
 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
-- 
2.11.0