Changing the LCR register after initialization does not seem to be
reliable on all chips (particularly not on CH341A). Restructure
initialization and configuration to always reinit the chip on
configuration changes instead and pass the LCR register value directly
to the initialization command.
Cleaned-up version of a patch by Grigori Goronzy
Signed-off-by: Aidan Thornton <makosoft@xxxxxxxxx>
---
drivers/usb/serial/ch341.c | 38 ++++++++++++++++++++------------------
1 file changed, 20 insertions(+), 18 deletions(-)
diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index bdf525f..ce799d0 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -132,10 +132,10 @@ static int ch341_control_in(struct usb_device *dev,
return r;
}
-static int ch341_set_baudrate(struct usb_device *dev,
- struct ch341_private *priv)
+static int ch341_init_set_baudrate(struct usb_device *dev,
+ struct ch341_private *priv, unsigned ctrl)
{
- short a, b;
+ short a;
int r;
unsigned long factor;
short divisor;
@@ -155,11 +155,9 @@ static int ch341_set_baudrate(struct usb_device *dev,
factor = 0x10000 - factor;
a = (factor & 0xff00) | divisor;
- b = factor & 0xff;
- r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, a);
- if (!r)
- r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x0f2c, b);
+ /* 0x9c is "enable SFR_UART Control register and timer" */
+ r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0x9c | (ctrl << 8), a | 0x80);
return r;
}
@@ -218,16 +216,12 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
if (r < 0)
goto out;
- r = ch341_set_baudrate(dev, 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);
+ r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, 0x00c3);
if (r < 0)
goto out;
@@ -236,11 +230,7 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
if (r < 0)
goto out;
- r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0x501f, 0xd90a);
- if (r < 0)
- goto out;
-
- r = ch341_set_baudrate(dev, priv);
+ r = ch341_init_set_baudrate(dev, priv, 0);
if (r < 0)
goto out;
@@ -355,16 +345,28 @@ static void ch341_set_termios(struct tty_struct *tty,
struct ch341_private *priv = usb_get_serial_port_data(port);
unsigned baud_rate;
unsigned long flags;
+ unsigned char ctrl;
+ int r;
+
+ /* redundant changes may cause the chip to lose bytes */
+ if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
+ return;
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);
- ch341_set_baudrate(port->serial->dev, priv);
+ r = ch341_init_set_baudrate(port->serial->dev, priv, ctrl);
+ if (r < 0 && old_termios) {
+ priv->baud_rate = tty_termios_baud_rate(old_termios);
+ tty_termios_copy_hw(&tty->termios, old_termios);
+ }
} else {
spin_lock_irqsave(&priv->lock, flags);
priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
--
2.10.0
--
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