Recently my tuner cards have been swapping the IDs assigned to them by udev which has caused MythTV to miss some recordings (it was attempting to record HD content on an SD card) This is easy to solve using udev rules to create symlinked adapaters that I could use in MythTV instead. Info on how to do this can be found at http://www.mythtv.org/wiki/Device_Filenames_and_udev#Example_DVB_udev_Rules_file
My udev file is repeated below, I have a Nova-T SD tuner card and a TBS 6280 Dual Freeview HD, for some reason it would not work with and underscore between adapater and tbs1 in /dev/dvb/adapter-tbs1/
# /etc/udev/rules.d/10-dvb.rules
#
# To Identify serial nos etc for a Device call
# udevadm info -a -p $(udevadm info -q path -n /dev/dvb/adapter0/frontend0)
#
# use the following to test
#
# udevadm control --log-priority="debug-verbose"
# udevadm test /class/dvb/dvb0.frontend0
#
# http://www.mythtv.org/wiki/Device_Filenames_and_udev
# Create a symlink for single tuner Nova T device
SUBSYSTEM=="dvb", ATTRS{vendor}=="0x14f1", ATTRS{device}=="0x8802", PROGRAM="/bin/sh -c 'K=%k; K=$${K#dvb}; printf dvb/adapter_nova-t1/%%s $${K#*.}'", SYMLINK+="%c"
# Create a symlinks for both tuners of TBS device
SUBSYSTEM=="dvb", ATTRS{vendor}=="0x1131", ATTRS{device}=="0x7160", PROGRAM="/bin/sh -c 'set -xv ; K=%k; K=$${K#dvb}; N=$${K#*.}; if [ ! -e /dev/dvb/adapter-tbs1/$N ] ; then printf dvb/adapter-tbs1/%%s $${K#*.}; else printf dvb/adapter-tbs2/%%s $${K#*.}; fi ; exit 0'", SYMLINK+="%c"
