--- ch341.c 2019-10-24 15:02:10.039646991 +0800 +++ ch341.c 2019-10-24 15:06:14.244416258 +0800 @@ -358,6 +358,7 @@ struct ch341_private *priv = usb_get_serial_port_data(port); unsigned baud_rate; unsigned long flags; + unsigned int par_flags; baud_rate = tty_get_baud_rate(tty); @@ -371,6 +372,30 @@ * (cflag & PARENB) : parity {NONE, EVEN, ODD} * (cflag & CSTOPB) : stop bits [1, 2] */ + /* CH340 doesn't appear to support variable stop bits or data bits */ + if (C_PARENB(tty)) { + if (C_PARODD(tty)) { + if (tty->termios.c_cflag & CMSPAR) { + dev_dbg(&port->dev, "parity = mark\n"); + par_flags = 0xeb; + } else { + dev_dbg(&port->dev, "parity = odd\n"); + par_flags = 0xcb; + } + } else { + if (tty->termios.c_cflag & CMSPAR) { + dev_dbg(&port->dev, "parity = space\n"); + par_flags = 0xfb; + } else { + dev_dbg(&port->dev, "parity = even\n"); + par_flags = 0xdb; + } + } + } else { + dev_dbg(&port->dev, "parity = none\n"); + par_flags = 0xc3; + } + ch341_control_out(port->serial->dev, 0x9a, 0x2518, par_flags); spin_lock_irqsave(&priv->lock, flags); if (C_BAUD(tty) == B0)