USB: ftdi_sio: fix DTR/RTS line modes

commit 6a1a82df91fa0eb1cc76069a9efe5714d087eccd upstream.

Call set_mctrl() and clear_mctrl() according to the flow control mode
selected. This makes serial communication for FT232 connected devices
work when CRTSCTS is not set.

This fixes a regression introduced by 4175f3e31 ("tty_port: If we are
opened non blocking we still need to raise the carrier"). This patch
calls the low-level driver's dtr_rts() function which consequently sets
TIOCM_DTR | TIOCM_RTS. A later call to set_termios() without CRTSCTS in
cflags, however, does not reset these bits, and so data is not actually
sent out on the serial wire.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Johan Hovold <jhovold@gmail.com>
Cc: Alan Cox <alan@linux.intel.com>
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 9cf46526a967b3b71ef44fc75e1b9399850ba798..bf56be19d7b2f5ff925afb0118d14825fa5b7638 100644 (file)
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -2306,6 +2306,8 @@ 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
@@ -2353,6 +2355,8 @@ static void ftdi_set_termios(struct tty_struct *tty,
                        }
                }
 
+               /* lower DTR/RTS */
+               clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
        }
        return;
 }