* [PATCH] USB: serial: ftdi_sio: fix FTX sub-integer prescaler
@ 2021-01-26 13:59 Johan Hovold
2021-01-26 14:11 ` Johan Hovold
0 siblings, 1 reply; 3+ messages in thread
From: Johan Hovold @ 2021-01-26 13:59 UTC (permalink / raw)
To: linux-usb; +Cc: Johan Hovold, Vladimir, stable
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 12 MBd.
Reported-by: Vladimir <svv75@mail.ru>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=210351
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/usb/serial/ftdi_sio.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 94398f89e600..4168801b9595 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1386,8 +1386,9 @@ static int change_speed(struct tty_struct *tty, struct usb_serial_port *port)
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);
--
2.26.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] USB: serial: ftdi_sio: fix FTX sub-integer prescaler
2021-01-26 13:59 [PATCH] USB: serial: ftdi_sio: fix FTX sub-integer prescaler Johan Hovold
@ 2021-01-26 14:11 ` Johan Hovold
2021-01-26 14:22 ` Johan Hovold
0 siblings, 1 reply; 3+ messages in thread
From: Johan Hovold @ 2021-01-26 14:11 UTC (permalink / raw)
To: linux-usb; +Cc: Johan Hovold, Vladimir, stable
On Tue, Jan 26, 2021 at 02:59:17PM +0100, Johan Hovold wrote:
> 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 12 MBd.
Hmm. I played around with this using an FT232H which has a 12 MHz clock
so this example is off for FTX. I'll fix it up before applying.
Johan
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] USB: serial: ftdi_sio: fix FTX sub-integer prescaler
2021-01-26 14:11 ` Johan Hovold
@ 2021-01-26 14:22 ` Johan Hovold
0 siblings, 0 replies; 3+ messages in thread
From: Johan Hovold @ 2021-01-26 14:22 UTC (permalink / raw)
To: linux-usb; +Cc: Johan Hovold, Vladimir, stable
On Tue, Jan 26, 2021 at 03:11:15PM +0100, Johan Hovold wrote:
> On Tue, Jan 26, 2021 at 02:59:17PM +0100, Johan Hovold wrote:
> > 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 12 MBd.
>
> Hmm. I played around with this using an FT232H which has a 12 MHz clock
> so this example is off for FTX. I'll fix it up before applying.
Nope, false alarm, it still holds.
Johan
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-01-26 14:23 UTC | newest]
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2021-01-26 13:59 [PATCH] USB: serial: ftdi_sio: fix FTX sub-integer prescaler Johan Hovold
2021-01-26 14:11 ` Johan Hovold
2021-01-26 14:22 ` Johan Hovold
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