diff options
Diffstat (limited to 'drivers/usb/serial/ch341.c')
| -rw-r--r-- | drivers/usb/serial/ch341.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c index df582fe855f0..c5ecdcd51ffc 100644 --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -205,6 +205,16 @@ static int ch341_get_divisor(speed_t speed) 16 * speed - 16 * CH341_CLKRATE / (clk_div * (div + 1))) div++; + /* + * Prefer lower base clock (fact = 0) if even divisor. + * + * Note that this makes the receiver more tolerant to errors. + */ + if (fact == 1 && div % 2 == 0) { + div /= 2; + fact = 0; + } + return (0x100 - div) << 8 | fact << 2 | ps; } @@ -642,9 +652,13 @@ static int ch341_tiocmget(struct tty_struct *tty) static int ch341_reset_resume(struct usb_serial *serial) { struct usb_serial_port *port = serial->port[0]; - struct ch341_private *priv = usb_get_serial_port_data(port); + struct ch341_private *priv; int ret; + priv = usb_get_serial_port_data(port); + if (!priv) + return 0; + /* reconfigure ch341 serial port after bus-reset */ ch341_configure(serial->dev, priv); |