USB: serial: ch341: fix open and resume after B0

commit a20047f36e2f6a1eea4f1fd261aaa55882369868 upstream.

The private baud_rate variable is used to configure the port at open and
reset-resume and must never be set to (and left at) zero or reset-resume
and all further open attempts will fail.

Fixes: aa91def41a7b ("USB: ch341: set tty baud speed according to tty
struct")
Fixes: 664d5df92e88 ("USB: usb-serial ch341: support for DTR/RTS/CTS")
Signed-off-by: Johan Hovold <johan@kernel.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 5171fc3..db5b7bb 100644 (file)
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -366,14 +366,15 @@ static void ch341_set_termios(struct tty_struct *tty,
 
        baud_rate = tty_get_baud_rate(tty);
 
-       priv->baud_rate = baud_rate;
-
        ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
 
        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);
                if (r < 0 && old_termios) {
                        priv->baud_rate = tty_termios_baud_rate(old_termios);