this happens on bootup up of a linux-2.6.23.1 amd64 deb kernel, probably when mythtv-backend is starts since a /etc/init.d/mythtv-backend restart produces the same messages and although mythtv-bankend runs, it can't see the hauppauge 150 tuner. 32-bit kernel works fine.
ioctl32(mythbackend:3924): Unknown cmd fd(4) cmd(80685600){t:'V';sz:104} arg(fff514dc) on /dev/video0
ioctl32(mythbackend:3924): Unknown cmd fd(4) cmd(80685600){t:'V';sz:104} arg(fff51498) on /dev/video0
ioctl32(mythbackend:3924): Unknown cmd fd(4) cmd(803c7601){t:'v';sz:60} arg(fff51500) on /dev/video0
ioctl32(mythbackend:3924): Unknown cmd fd(4) cmd(80685600){t:'V';sz:104} arg(fff5127c) on /dev/video0
ioctl32(mythbackend:3924): Unknown cmd fd(4) cmd(803c7601){t:'v';sz:60} arg(fff5138c) on /dev/video0