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Commit 7041d9c3 authored by Florian Zumbiehl's avatar Florian Zumbiehl Committed by Johan Hovold
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USB: serial: pl2303: add support for tx xon/xoff flow control 



Support hardware-level Xon/Xoff flow control in transmit direction with
pl2303.

I only know how to get the hardware to do IXON/!IXANY with ^S/^Q as control
characters, so I preserve the old behaviour for all other cases.

Signed-off-by: default avatarFlorian Zumbiehl <florz@florz.de>
[ johan: rewrite logic using pl2303_termios_change() helper ]
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
parent 7b0c6b38

drivers/usb/serial/pl2303.c

+15 −1
Original line number Diff line number Diff line
@@ -533,6 +533,17 @@ static int pl2303_set_line_request(struct usb_serial_port *port, 
	return 0;

}



static bool pl2303_termios_change(const struct ktermios *a, const struct ktermios *b)

{

	bool ixon_change;



	ixon_change = ((a->c_iflag ^ b->c_iflag) & (IXON | IXANY)) ||

			a->c_cc[VSTART] != b->c_cc[VSTART] ||

			a->c_cc[VSTOP] != b->c_cc[VSTOP];



	return tty_termios_hw_change(a, b) || ixon_change;

}



static void pl2303_set_termios(struct tty_struct *tty,

		struct usb_serial_port *port, struct ktermios *old_termios)

{
@@ -544,7 +555,7 @@ static void pl2303_set_termios(struct tty_struct *tty, 
	int ret;

	u8 control;



	if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))

	if (old_termios && !pl2303_termios_change(&tty->termios, old_termios))

		return;



	buf = kzalloc(7, GFP_KERNEL);
@@ -662,6 +673,9 @@ 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) {

		pl2303_vendor_write(serial, 0x0, 0xc0);

	} else {

		pl2303_vendor_write(serial, 0x0, 0x0);

	}