Patch "USB: serial: ch341: fix modem-control and B0 handling" has been added to the 4.4-stable tree

[<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 the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-serial-ch341-fix-modem-control-and-b0-handling.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>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

From: Johan Hovold <johan@kernel.org>

commit 030ee7ae52a46a2be52ccc8242c4a330aba8d38e upstream.

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")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/serial/ch341.c |   18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -362,24 +362,24 @@ static void ch341_set_termios(struct tty
 	baud_rate = tty_get_baud_rate(tty);
 
 	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;
 		ch341_set_baudrate(port->serial->dev, priv);
-	} 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);
-
 	/* Unimplemented:
 	 * (cflag & CSIZE) : data bits [5, 8]
 	 * (cflag & PARENB) : parity {NONE, EVEN, ODD}
 	 * (cflag & CSTOPB) : stop bits [1, 2]
 	 */
+
+	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)


Patches currently in stable-queue which might be from johan@kernel.org are

queue-4.4/usb-serial-ch341-fix-modem-control-and-b0-handling.patch
queue-4.4/powerpc-ibmebus-fix-further-device-reference-leaks.patch
queue-4.4/usb-serial-ch341-fix-control-message-error-handling.patch
queue-4.4/usb-serial-ch341-fix-open-and-resume-after-b0.patch
queue-4.4/usb-serial-ch341-fix-open-error-handling.patch
queue-4.4/usb-serial-ch341-fix-initial-modem-control-state.patch
queue-4.4/bus-vexpress-config-fix-device-reference-leak.patch
queue-4.4/powerpc-ibmebus-fix-device-reference-leaks-in-sysfs-interface.patch
queue-4.4/usb-serial-kl5kusb105-fix-line-state-error-handling.patch
queue-4.4/usb-serial-ch341-fix-resume-after-reset.patch