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FAILED: patch "[PATCH] USB: serial: ch341: fix modem-control and B0 handling" failed to apply to 4.4-stable tree

PATCH [email protected] 1 participant 1 message Jan 17, 2017

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The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From 030ee7ae52a46a2be52ccc8242c4a330aba8d38e Mon Sep 17 00:00:00 2001

From: Johan Hovold <[email protected]>
Date: Fri, 6 Jan 2017 19:15:12 +0100
Subject: [PATCH] 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 <[email protected]>
Signed-off-by Johan Hovold <[email protected]>
drivers/usb/serial/ch341.c +7 -9
index 6279df905c14..0cc5056b304d 100644
@@ -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)