When ASYNC_SPD_CUST is used, update custom_divisor field for TIOCGSERIAL
and c_*speed fields for TCGETS2 so that they correspond to the newly set
baud rate value.
So userspace TCGETS2 ioctls in new c_*speed fields will see the true baud
rate that is being used.
This is needed for switching userspace applications to use TCGETS2 API as
currently new c_*speed fields does not report correct values. Without this
change userspace applications still have to use old deprecated TIOCGSERIAL
to retrieve current baud rate.
Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
Tested-by: Marek Behún <kabel@xxxxxxxxxx>
Signed-off-by: Marek Behún <kabel@xxxxxxxxxx>
---
Please note that if c_*speed fields of TCGETS2 are not going to be fixed
then userspace application cannot be switched to use this new TCGETS2 API
due to this issue.
---
drivers/usb/serial/ftdi_sio.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 718c86db2900..79b00912c81c 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1319,6 +1319,7 @@ static u32 get_ftdi_divisor(struct tty_struct *tty,
{
struct ftdi_private *priv = usb_get_serial_port_data(port);
struct device *dev = &port->dev;
+ int fix_custom_divisor = 0;
u32 div_value = 0;
int div_okay = 1;
int baud;
@@ -1333,6 +1334,7 @@ static u32 get_ftdi_divisor(struct tty_struct *tty,
if (baud == 38400 &&
((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST) &&
(priv->custom_divisor)) {
+ fix_custom_divisor = 1;
baud = DIV_ROUND_CLOSEST(priv->baud_base, priv->custom_divisor);
dev_dbg(dev, "%s - custom divisor %d sets baud rate to %d\n",
__func__, priv->custom_divisor, baud);
@@ -1426,7 +1428,19 @@ static u32 get_ftdi_divisor(struct tty_struct *tty,
ftdi_chip_name[priv->chip_type]);
}
+ /* Fix deprecated async-compatible custom_divisor hack and update tty baud rate */
+ if (fix_custom_divisor) {
+ priv->custom_divisor = DIV_ROUND_CLOSEST(priv->baud_base, baud);
+ old_baud = baud;
+ baud = 38400;
+ }
+
tty_encode_baud_rate(tty, baud, baud);
+
+ /* For async-compatible custom_divisor store into TCGETS2 c_*speed fields real baud rate */
+ if (fix_custom_divisor)
+ tty->termios.c_ispeed = tty->termios.c_ospeed = old_baud;
+
return div_value;
}
@@ -2699,6 +2713,8 @@ static void ftdi_set_termios(struct tty_struct *tty,
dev_dbg(ddev, "%s: forcing baud rate for this device\n", __func__);
tty_encode_baud_rate(tty, priv->force_baud,
priv->force_baud);
+ termios->c_ispeed = termios->c_ospeed =
+ DIV_ROUND_CLOSEST(priv->baud_base, priv->custom_divisor);
}
/* Force RTS-CTS if this device requires it. */
--
2.20.1
