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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 );
}
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