[PATCH 5.4 249/340] USB: serial: ftdi_sio: fix FTX sub-integer prescaler

From: Greg Kroah-Hartman
Date: Mon Mar 01 2021 - 17:45:39 EST


From: Johan Hovold <johan@xxxxxxxxxx>

commit 528222d0c8ce93e435a95cd1e476b60409dd5381 upstream.

The most-significant bit of the sub-integer-prescaler index is set in
the high byte of the baudrate request wIndex also for FTX devices.

This fixes rates like 1152000 which got mapped to 1.2 MBd.

Reported-by: Vladimir <svv75@xxxxxxx>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=210351
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/serial/ftdi_sio.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1386,8 +1386,9 @@ static int change_speed(struct tty_struc
index_value = get_ftdi_divisor(tty, port);
value = (u16)index_value;
index = (u16)(index_value >> 16);
- if ((priv->chip_type == FT2232C) || (priv->chip_type == FT2232H) ||
- (priv->chip_type == FT4232H) || (priv->chip_type == FT232H)) {
+ if (priv->chip_type == FT2232C || priv->chip_type == FT2232H ||
+ priv->chip_type == FT4232H || priv->chip_type == FT232H ||
+ priv->chip_type == FTX) {
/* Probably the BM type needs the MSB of the encoded fractional
* divider also moved like for the chips above. Any infos? */
index = (u16)((index << 8) | priv->interface);