USB: serial: ch341: change initial line-control settings

Some CH340 devices appear unable to change the initial LCR settings, so
set a sane 8N1 default during probe to enable basic support for such
devices.

Also drop a redundant LCR read during device initialisation.

Signed-off-by: Johan Hovold <johan@kernel.org>

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index c51ec9802856dde5fde3b8cf8e75d82d7d190257..351745aec0e130786c815e5b81ceec22e918e841 100644 (file)
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -238,15 +238,6 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
        if (r < 0)
                goto out;
 
-       /* expect two bytes 0x56 0x00 */
-       r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x2518, 0, buffer, size);
-       if (r < 0)
-               goto out;
-
-       r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, 0x0050);
-       if (r < 0)
-               goto out;
-
        r = ch341_set_baudrate_lcr(dev, priv, priv->lcr);
        if (r < 0)
                goto out;
@@ -268,6 +259,11 @@ static int ch341_port_probe(struct usb_serial_port *port)
 
        spin_lock_init(&priv->lock);
        priv->baud_rate = DEFAULT_BAUD_RATE;
+       /*
+        * Some CH340 devices appear unable to change the initial LCR
+        * settings, so set a sane 8N1 default.
+        */
+       priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
 
        r = ch341_configure(port->serial->dev, priv);
        if (r < 0)