From: Jan Niehusmann <jan@gondor.com>
Subject: Patch to fix setting USB-serial adapters to 38400 bps
Bug-Debian: http://bugs.debian.org/740098
Forwarded: no
Description: The following patch should fix the reported issue.
 .
 On serial ports not supporting the TIOCGSERIAL/TIOCSSERIAL mechanism,
 this still means that the custom baud rates do not work, but at least
 38400 works, again.
 .
 Perhaps an even better fix would be switching to the newer termios2 API,
 as described here:
 https://mail.python.org/pipermail/python-list/2012-October/633871.html
 .
 That API allows setting custom baud rates on the USB serial adapters I
 have tested, where TIOCGSERIAL/TIOCSSERIAL was not supported.
 .
 But unfortunately, termios2 is not available through glibc, so one would
 need to call linux-specific ioctls directly, which wouldn't be portable
 at all, and I don't know how it interacts with the BSD / Hurd ports.
 .
 Therefore this is the minimal fix, for now.
Upstream-Status: Pending

--- a/src/SerialImp.c
+++ b/src/SerialImp.c
@@ -872,10 +872,14 @@
 	   out and select baud rates 38400 then 28800 then 38400, you will get
 	   a final baud rate of 28800 because you did not update the divisor.
 
+	   However, if the serial port doesn't support TIOCGSERIAL or custom speeds,
+	   don't fail: In this case, just use B38400 and assume that there is no way
+	   to set a custom speed on this port.
+
 	   See the next ifdef below for the divisor.
 	*/
 #if defined(TIOCGSERIAL)
-	if ( cspeed == B38400 )
+	if ( cspeed == B38400 && ioctl( fd, TIOCGSERIAL, &sstruct ) == 0 )
 		cspeed = 38400;
 #endif /* TIOCGSERIAL */
 	if(     cfsetispeed( &ttyset, cspeed ) < 0 ||
@@ -905,10 +909,9 @@
 			return(1);
 		}
 		sstruct.custom_divisor = ( sstruct.baud_base/cspeed );
-		cspeed = B38400;
 #endif /* TIOCGSERIAL */
-		if(     cfsetispeed( &ttyset, cspeed ) < 0 ||
-			cfsetospeed( &ttyset, cspeed ) < 0 )
+		if(     cfsetispeed( &ttyset, B38400 ) < 0 ||
+			cfsetospeed( &ttyset, B38400 ) < 0 )
 		{
 			/* OK, we tried everything */
 			report( "nativeSetSerialPortParams: Cannot Set Speed\n" );
@@ -916,8 +919,11 @@
 		}
 #if defined(TIOCSSERIAL)
 		/*  It is assumed Win32 does this for us */
+		/*  Ignore errors if the target speed is 38400: In this case,
+		 *  just assume TIOCSSERIAL is not supported and custom speeds are
+		 *  not available. */
 		if (	sstruct.baud_base < 1 ||
-		ioctl( fd, TIOCSSERIAL, &sstruct ) < 0 )
+		ioctl( fd, TIOCSSERIAL, &sstruct ) < 0 && cspeed != 38400 )
 		{
 			return( 1 );
 		}