use set_serial to switch to low latency mode on serial device

contrib/debian/init.d/ebusd

@@ -29,10 +29,16 @@ instance="EBUSD_OPTS$2"
 instance=${!instance}
 
 start_instance () {
-	local opts suffix
+	local opts suffix dev
 	opts=$1
 	shift
 	suffix="${opts#EBUSD_OPTS}"
+	dev=`echo " ${!opts}"|sed -e 's#^.* -d ##' -e 's# -.*$##'`
+	if [ -n "$dev" ] && [ "${dev:0:5}" == '/dev/' ] && [ -c "$dev" ] && [ -x /bin/setserial ]; then
+		log_daemon_msg "Setting low latency for ebusd${suffix} device"
+		/bin/setserial "$dev" low_latency
+		log_end_msg $?
+	fi
 	log_daemon_msg "Starting ebusd${suffix}" ebusd
 	pidfile=$PIDFILE_PREFIX${suffix}$PIDFILE_SUFFIX
 	start-stop-daemon --start --quiet --oknodo --pidfile $pidfile --exec $DAEMON -- --pidfile $pidfile ${!opts}

make_debian.sh

@@ -70,7 +70,7 @@ Architecture: $ARCH
 Maintainer: John Baier <ebusd@ebusd.eu>
 Homepage: https://github.com/john30/ebusd
 Bugs: https://github.com/john30/ebusd/issues
-Depends: libstdc++6 (>= 4.8.1), libc6, libgcc1$extralibs
+Depends: setserial, libstdc++6 (>= 4.8.1), libc6, libgcc1$extralibs
 Description: eBUS daemon.
  ebusd is a daemon for handling communication with eBUS devices connected to a
  2-wire bus system.