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USB: serial: pl2303: fix line-speed handling on newer chips

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commit 979d9cbe75 upstream.

The latest chip family (HXN) apparently does not support setting the
line speed using divisors and instead needs to use the direct encoding
scheme for all rates.

This specifically enables 50, 110, 134, 200 bps and other rates not
supported by the original chip type.

Fixes: ebd09f1cd4 ("USB: serial: pl2303: add support for PL2303HXN")
Cc: stable@vger.kernel.org      # 5.5
Cc: Charles Yeh <charlesyeh522@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2021-01-11 18:00:19 +01:00 committed by Greg Kroah-Hartman
parent b006da9e3e
commit 11fd58946e
1 changed files with 7 additions and 1 deletions
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8
drivers/usb/serial/pl2303.c
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@ -183,6 +183,7 @@ struct pl2303_type_data {
speed_t max_baud_rate;
unsigned long quirks;
unsigned int no_autoxonxoff:1;
unsigned int no_divisors:1;
};
struct pl2303_serial_private {
@ -209,6 +210,7 @@ static const struct pl2303_type_data pl2303_type_data[TYPE_COUNT] = {
},
[TYPE_HXN] = {
.max_baud_rate = 12000000,
.no_divisors = true,
},
};
@ -571,8 +573,12 @@ static void pl2303_encode_baud_rate(struct tty_struct *tty,
baud = min_t(speed_t, baud, spriv->type->max_baud_rate);
/*
* Use direct method for supported baud rates, otherwise use divisors.
* Newer chip types do not support divisor encoding.
*/
baud_sup = pl2303_get_supported_baud_rate(baud);
if (spriv->type->no_divisors)
baud_sup = baud;
else
baud_sup = pl2303_get_supported_baud_rate(baud);
if (baud == baud_sup)
baud = pl2303_encode_baud_rate_direct(buf, baud);