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 <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
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(-)
diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 3a48302c1cd5..d23dfdd0247d 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -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)
--
2.10.2
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