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

PATCH In review Johan Hovold 2 participants 2 messages Jan 17, 2017 Stable branch

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Johan Hovold

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PATCH 1/1 USB: serial: ch341: fix modem-control and B0 handling

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")
Cc stable <[email protected]>
Signed-off-by Johan Hovold <[email protected]>

---

This is a backport of 030ee7ae52a4 ("USB: serial: ch341: fix modem-control and B0 handling") to 4.9 that should apply also to 4.4.

Johan

 drivers/usb/serial/ch341.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)
drivers/usb/serial/ch341.c +9 -9
index 3a48302c1cd5..d23dfdd0247d 100644
@@ -345,24 +345,24 @@ static void ch341_set_termios(struct tty_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)
Signature · 1 line
2.10.2
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#1 lore raw
Quoted 9 lines · Johan Hovold

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.

Quoted 7 lines
Fixes 664d5df92e88 ("USB: usb-serial ch341: support for DTR/RTS/CTS")
Cc stable <[email protected]>
Signed-off-by Johan Hovold <[email protected]>

---

This is a backport of 030ee7ae52a4 ("USB: serial: ch341: fix modem-control and B0 handling") to 4.9 that should apply also to 4.4.

Thanks for the backport, now applied.

greg k-h