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 <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 030ee7ae52a46a2be52ccc8242c4a330aba8d38e Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@xxxxxxxxxx>
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 <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
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)
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html