Commit 4e46c410 authored by Aidan Thornton's avatar Aidan Thornton Committed by Johan Hovold

USB: serial: ch341: reinitialize chip on reconfiguration

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.

(Note that baud rates above 500kbaud are incorrect, but they're incorrect in
the same way both before and after this patch at least on the CH340G. Fixing
this isn't a priority as higher baud rates don't seem that reliable anyway.)

Cleaned-up version of a patch by Grigori Goronzy
Signed-off-by: default avatarAidan Thornton <makosoft@gmail.com>
Reviewed-by: default avatarGrigori Goronzy <greg@chown.ath.cx>
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
parent 6fde8d29
...@@ -132,10 +132,10 @@ static int ch341_control_in(struct usb_device *dev, ...@@ -132,10 +132,10 @@ static int ch341_control_in(struct usb_device *dev,
return r; return r;
} }
static int ch341_set_baudrate(struct usb_device *dev, static int ch341_init_set_baudrate(struct usb_device *dev,
struct ch341_private *priv) struct ch341_private *priv, unsigned ctrl)
{ {
short a, b; short a;
int r; int r;
unsigned long factor; unsigned long factor;
short divisor; short divisor;
...@@ -155,11 +155,10 @@ static int ch341_set_baudrate(struct usb_device *dev, ...@@ -155,11 +155,10 @@ static int ch341_set_baudrate(struct usb_device *dev,
factor = 0x10000 - factor; factor = 0x10000 - factor;
a = (factor & 0xff00) | divisor; a = (factor & 0xff00) | divisor;
b = factor & 0xff;
r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, a); /* 0x9c is "enable SFR_UART Control register and timer" */
if (!r) r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT,
r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x0f2c, b); 0x9c | (ctrl << 8), a | 0x80);
return r; return r;
} }
...@@ -218,10 +217,6 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv) ...@@ -218,10 +217,6 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
if (r < 0) if (r < 0)
goto out; goto out;
r = ch341_set_baudrate(dev, priv);
if (r < 0)
goto out;
/* expect two bytes 0x56 0x00 */ /* expect two bytes 0x56 0x00 */
r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x2518, 0, buffer, size); r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x2518, 0, buffer, size);
if (r < 0) if (r < 0)
...@@ -236,11 +231,7 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv) ...@@ -236,11 +231,7 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
if (r < 0) if (r < 0)
goto out; goto out;
r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0x501f, 0xd90a); r = ch341_init_set_baudrate(dev, priv, 0);
if (r < 0)
goto out;
r = ch341_set_baudrate(dev, priv);
if (r < 0) if (r < 0)
goto out; goto out;
...@@ -355,16 +346,28 @@ static void ch341_set_termios(struct tty_struct *tty, ...@@ -355,16 +346,28 @@ static void ch341_set_termios(struct tty_struct *tty,
struct ch341_private *priv = usb_get_serial_port_data(port); struct ch341_private *priv = usb_get_serial_port_data(port);
unsigned baud_rate; unsigned baud_rate;
unsigned long flags; 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); baud_rate = tty_get_baud_rate(tty);
priv->baud_rate = baud_rate; priv->baud_rate = baud_rate;
ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
if (baud_rate) { if (baud_rate) {
spin_lock_irqsave(&priv->lock, flags); spin_lock_irqsave(&priv->lock, flags);
priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS); priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
spin_unlock_irqrestore(&priv->lock, flags); 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 { } else {
spin_lock_irqsave(&priv->lock, flags); spin_lock_irqsave(&priv->lock, flags);
priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS); priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment