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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>
This commit is contained in:
Johan Hovold 2017-01-06 19:15:23 +01:00
parent 448b6dc5a9
commit 7c61b0d5e8
1 changed files with 5 additions and 9 deletions
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14
drivers/usb/serial/ch341.c
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@ -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)