From 72a755fce0243d4168a6153813a1b533b05a7d72 Mon Sep 17 00:00:00 2001 From: Peter Favrholdt Date: Thu, 22 Sep 2005 00:48:49 -0700 Subject: [PATCH] USB: ftdi_sio: allow baud rate to be changed without raising RTS and DTR I'm using a 2 port USB RS232 dongle to connect to a serial-IR cradle for a bar code reader). Detecting the baudrate of the serial-IR involves keeping DTR low while changing baudrate. This works using normal 16550A serial ports as well as the FTDI driver version 1.4.0 (Linux 2.6.8) but stopped working with the change to "ensure RTS and DTR are raised when changing baudrate" introduced in version 1.4.1 (Linux 2.6.9). The attached patch fixes this, so RTS and DTR is only raised when changing baudrate iff the previous baudrate was B0. Signed-off-by: Peter Favrholdt Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds --- drivers/usb/serial/ftdi_sio.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'drivers/usb/serial') diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c index 4e434cb10bb..5a8631c8a4a 100644 --- a/drivers/usb/serial/ftdi_sio.c +++ b/drivers/usb/serial/ftdi_sio.c @@ -1846,10 +1846,12 @@ static void ftdi_set_termios (struct usb_serial_port *port, struct termios *old_ } else { /* set the baudrate determined before */ if (change_speed(port)) { - err("%s urb failed to set baurdrate", __FUNCTION__); + err("%s urb failed to set baudrate", __FUNCTION__); + } + /* Ensure RTS and DTR are raised when baudrate changed from 0 */ + if ((old_termios->c_cflag & CBAUD) == B0) { + set_mctrl(port, TIOCM_DTR | TIOCM_RTS); } - /* Ensure RTS and DTR are raised */ - set_mctrl(port, TIOCM_DTR | TIOCM_RTS); } /* Set flow control */ -- cgit v1.2.3