From 68270dab97107b5679080b596aa2f5a360f79873 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Tue, 2 Apr 2019 10:19:30 +0200 Subject: [PATCH] USB: serial: pl2303: fix non-supported xon/xoff Older pl2303 devices do not support automatic xon/xoff flow control, so add add a flag to prevent trying to enable it for legacy device types. Refactor the IXON test into a helper function to improve readability. Fixes: 7041d9c3f01b ("USB: serial: pl2303: add support for tx xon/xoff flow control") Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold --- drivers/usb/serial/pl2303.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c index bb3f9aa4a909..f1d904706758 100644 --- a/drivers/usb/serial/pl2303.c +++ b/drivers/usb/serial/pl2303.c @@ -156,6 +156,7 @@ enum pl2303_type { struct pl2303_type_data { speed_t max_baud_rate; unsigned long quirks; + unsigned int no_autoxonxoff:1; }; struct pl2303_serial_private { @@ -173,11 +174,12 @@ struct pl2303_private { static const struct pl2303_type_data pl2303_type_data[TYPE_COUNT] = { [TYPE_01] = { - .max_baud_rate = 1228800, - .quirks = PL2303_QUIRK_LEGACY, + .max_baud_rate = 1228800, + .quirks = PL2303_QUIRK_LEGACY, + .no_autoxonxoff = true, }, [TYPE_HX] = { - .max_baud_rate = 12000000, + .max_baud_rate = 12000000, }, }; @@ -552,6 +554,20 @@ static bool pl2303_termios_change(const struct ktermios *a, const struct ktermio return tty_termios_hw_change(a, b) || ixon_change; } +static bool pl2303_enable_xonxoff(struct tty_struct *tty, const struct pl2303_type_data *type) +{ + if (!I_IXON(tty) || I_IXANY(tty)) + return false; + + if (START_CHAR(tty) != 0x11 || STOP_CHAR(tty) != 0x13) + return false; + + if (type->no_autoxonxoff) + return false; + + return true; +} + static void pl2303_set_termios(struct tty_struct *tty, struct usb_serial_port *port, struct ktermios *old_termios) { @@ -681,8 +697,7 @@ static void pl2303_set_termios(struct tty_struct *tty, pl2303_vendor_write(serial, 0x0, 0x41); else pl2303_vendor_write(serial, 0x0, 0x61); - } else if (I_IXON(tty) && !I_IXANY(tty) && START_CHAR(tty) == 0x11 && - STOP_CHAR(tty) == 0x13) { + } else if (pl2303_enable_xonxoff(tty, spriv->type)) { pl2303_vendor_write(serial, 0x0, 0xc0); } else { pl2303_vendor_write(serial, 0x0, 0x0);