Support hardware-level Xon/Xoff flow control in transmit direction with
pl2303.
Signed-off-by: Florian Zumbiehl <florz@xxxxxxxx>
---
Note that the patch has only been fully tested with kernel 4.9.28, and
test-compiled against 4.16.8. Tested only with the pl2303 adapters I have
available (which seem to be type 0 if I interpret the code correctly), I
don't have a clue whether this works with other versions of the chip.
--- linux-4.16.8/drivers/usb/serial/pl2303.c.orig 2018-05-09 09:53:14.000000000 +0200
+++ linux-4.16.8/drivers/usb/serial/pl2303.c 2018-05-14 04:32:27.860780856 +0200
@@ -544,8 +544,12 @@ static void pl2303_set_termios(struct tt
int ret;
u8 control;
- if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
- return;
+ if (old_termios &&
+ !(tty_termios_hw_change(&tty->termios, old_termios) ||
+ ((tty->termios.c_iflag ^ old_termios->c_iflag) & (IXON | IXANY)) ||
+ tty->termios.c_cc[VSTOP] != old_termios->c_cc[VSTOP] ||
+ tty->termios.c_cc[VSTART] != old_termios->c_cc[VSTART]))
+ return;
buf = kzalloc(7, GFP_KERNEL);
if (!buf) {
@@ -662,6 +666,9 @@ static void pl2303_set_termios(struct tt
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);
}
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