USB: ftdi_sio: revert "USB: ftdi_sio: fix DTR/RTS line modes"

This reverts commit 825a3309202b504b637d27c6beeb5a5e876b71d7.

RTS and DTR should not be modified based on CRTSCTS when calling
set_termios.

Modem control lines are raised at port open by the tty layer and should stay
raised regardless of whether hardware flow control is enabled or not.

This is in conformance with the way serial ports work today and many
applications depend on this behaviour to be able to talk to hardware
implementing hardware flow control (without the applications actually using
it).

Hardware which expects different behaviour on these lines can always
use TIOCMSET/TIOCMBI[SC] after port open to change them.

Reported-by: Daniel Mack <daniel@caiaq.de>
Reported-by: Dave Mielke <dave@mielke.cc>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 6e6b0da5928782f2083d64269fa934006e1fea36..42fea29637b32f144cb9d5144cd1c8be8b5d2621 100644 (file)
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -2029,8 +2029,6 @@ static void ftdi_set_termios(struct tty_struct *tty,
                                "urb failed to set to rts/cts flow control\n");
                }
 
-               /* raise DTR/RTS */
-               set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
        } else {
                /*
                 * Xon/Xoff code
@@ -2078,8 +2076,6 @@ static void ftdi_set_termios(struct tty_struct *tty,
                        }
                }
 
-               /* lower DTR/RTS */
-               clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
        }
        return;
 }