From: Pali Rohár <pali@xxxxxxxxxx> If setting new baud rate fails, all other drivers leave the device at previous baud rate, only ftdi_sio resets to 9600 Baud. Change this behavior to that of other drivers so that /dev/ttyUSB* devices behave in the same way. Signed-off-by: Pali Rohár <pali@xxxxxxxxxx> Tested-by: Marek Behún <kabel@xxxxxxxxxx> Signed-off-by: Marek Behún <kabel@xxxxxxxxxx> --- Greg pointed out that this make break some people's workflow, that they may depend on this behavior. This is of course possible, although IMO improbable: it would be weird to depend on the fall back to 9600 Baud on error, instead of expecting that the baud rate didn't change at all (like in other /dev/ttyUSB* drivers). Nonetheless if someone complains that they workflow got broken, we will need to revert this. --- drivers/usb/serial/ftdi_sio.c | 38 ++++++++++++++++++++++++----------- 1 file changed, 26 insertions(+), 12 deletions(-) diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c index 5b109714612f..cdbba1a9edd9 100644 --- a/drivers/usb/serial/ftdi_sio.c +++ b/drivers/usb/serial/ftdi_sio.c @@ -1299,7 +1299,7 @@ static int update_mctrl(struct usb_serial_port *port, unsigned int set, static u32 get_ftdi_divisor(struct tty_struct *tty, - struct usb_serial_port *port) + struct usb_serial_port *port, speed_t old_baud) { struct ftdi_private *priv = usb_get_serial_port_data(port); struct device *dev = &port->dev; @@ -1322,6 +1322,8 @@ static u32 get_ftdi_divisor(struct tty_struct *tty, __func__, priv->custom_divisor, baud); } + if (!baud) + baud = old_baud; if (!baud) baud = 9600; switch (priv->chip_type) { @@ -1330,8 +1332,12 @@ static u32 get_ftdi_divisor(struct tty_struct *tty, if (div_value == -1) { dev_dbg(dev, "%s - Baudrate (%d) requested is not supported\n", __func__, baud); - baud = 9600; + baud = old_baud ? old_baud : 9600; div_value = ftdi_sio_baud_to_divisor(baud); + if (div_value == -1) { + baud = 9600; + div_value = ftdi_sio_baud_to_divisor(baud); + } div_okay = 0; } break; @@ -1340,8 +1346,8 @@ static u32 get_ftdi_divisor(struct tty_struct *tty, div_value = ftdi_232am_baud_to_divisor(baud); } else { dev_dbg(dev, "%s - Baud rate too high!\n", __func__); - baud = 9600; - div_value = ftdi_232am_baud_to_divisor(9600); + baud = (old_baud >= 183 && old_baud <= 3000000) ? old_baud : 9600; + div_value = ftdi_232am_baud_to_divisor(baud); div_okay = 0; } break; @@ -1363,9 +1369,9 @@ static u32 get_ftdi_divisor(struct tty_struct *tty, div_value = ftdi_232bm_baud_to_divisor(baud); } else { dev_dbg(dev, "%s - Baud rate too high!\n", __func__); - div_value = ftdi_232bm_baud_to_divisor(9600); + baud = (old_baud >= 183 && old_baud <= 3000000) ? old_baud : 9600; + div_value = ftdi_232bm_baud_to_divisor(baud); div_okay = 0; - baud = 9600; } break; case FT2232H: /* FT2232H chip */ @@ -1377,9 +1383,14 @@ static u32 get_ftdi_divisor(struct tty_struct *tty, div_value = ftdi_232bm_baud_to_divisor(baud); } else { dev_dbg(dev, "%s - Baud rate too high!\n", __func__); - div_value = ftdi_232bm_baud_to_divisor(9600); + if (old_baud >= 183 && old_baud < 1200) { + baud = old_baud; + div_value = ftdi_232bm_baud_to_divisor(baud); + } else { + baud = (old_baud >= 1200 && old_baud <= 12000000) ? old_baud : 9600; + div_value = ftdi_2232h_baud_to_divisor(baud); + } div_okay = 0; - baud = 9600; } break; } /* priv->chip_type */ @@ -1394,7 +1405,7 @@ static u32 get_ftdi_divisor(struct tty_struct *tty, return div_value; } -static int change_speed(struct tty_struct *tty, struct usb_serial_port *port) +static int change_speed(struct tty_struct *tty, struct usb_serial_port *port, speed_t old_baud) { struct ftdi_private *priv = usb_get_serial_port_data(port); u16 value; @@ -1402,7 +1413,7 @@ static int change_speed(struct tty_struct *tty, struct usb_serial_port *port) u32 index_value; int rv; - index_value = get_ftdi_divisor(tty, port); + index_value = get_ftdi_divisor(tty, port, old_baud); value = (u16)index_value; index = (u16)(index_value >> 16); if (priv->chip_type == FT2232C || priv->chip_type == FT2232H || @@ -1525,7 +1536,7 @@ static int set_serial_info(struct tty_struct *tty, struct serial_struct *ss) if (priv->flags & ASYNC_SPD_MASK) dev_warn_ratelimited(&port->dev, "use of SPD flags is deprecated\n"); - change_speed(tty, port); + change_speed(tty, port, 0); } mutex_unlock(&priv->cfg_lock); return 0; @@ -2774,9 +2785,12 @@ static void ftdi_set_termios(struct tty_struct *tty, /* Drop RTS and DTR */ clear_mctrl(port, TIOCM_DTR | TIOCM_RTS); } else { + speed_t old_baud = + old_termios ? tty_termios_baud_rate(old_termios) : 0; + /* set the baudrate determined before */ mutex_lock(&priv->cfg_lock); - if (change_speed(tty, port)) + if (change_speed(tty, port, old_baud)) dev_err(ddev, "%s urb failed to set baudrate\n", __func__); mutex_unlock(&priv->cfg_lock); /* Ensure RTS and DTR are raised when baudrate changed from 0 */ -- 2.35.1