Check for B0 in a more idiomatic way and make sure to not enable RTS/CTS hardware flow control in B0 as it may override the control lines. Also make sure to only enable RTS/DTR if there's a transition from B0. v2: use c_cflag macros. v3: rebase. Signed-off-by: Grigori Goronzy <greg@xxxxxxxxxxxx> --- drivers/usb/serial/ch341.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c index 22cfd88..3ce2041 100644 --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -387,10 +387,12 @@ static void ch341_set_termios(struct tty_struct *tty, if (C_CSTOPB(tty)) ctrl |= CH341_LCR_STOP_BITS_2; - if (priv->baud_rate) { - spin_lock_irqsave(&priv->lock, flags); - priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS); - spin_unlock_irqrestore(&priv->lock, flags); + if (C_BAUD(tty) != B0) { + if (old_termios && (old_termios->c_cflag & CBAUD) == B0) { + spin_lock_irqsave(&priv->lock, flags); + priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS); + spin_unlock_irqrestore(&priv->lock, flags); + } r = ch341_init_set_baudrate(port->serial->dev, priv, ctrl); if (r < 0 && old_termios) { priv->baud_rate = tty_termios_baud_rate(old_termios); @@ -404,7 +406,7 @@ static void ch341_set_termios(struct tty_struct *tty, ch341_set_handshake(port->serial->dev, priv->line_control); - if (C_CRTSCTS(tty)) { + if (C_CRTSCTS(tty) && C_BAUD(tty) != B0) { r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG, CH341_REG_RTSCTS | ((uint16_t)CH341_REG_RTSCTS << 8), 0x0101); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html