If you’ve been trying to transfer a GPX file to your GPS unit from a Linux machine, using GPSBabel, and have seen this message:
$> gpsbabel -r -i gpx -f FOO.gpx -o garmin -F usb: usb_set_configuration failed, probably because kernel driver 'garmin_gps' is blocking our access to the USB device.
…then don’t despair. Help is here.
This error occurs because gpsbabel doesn’t use the kernel module garmin_gps, and that module gets in the way of other applications writing to the GPS device. The simple solution is to unload the blocking module thus:
sudo rmmod garmin_gps
which will then allow you to repeat the original command without problems. Note that removing the kernel module is temporary: without more jiggery pokery it will come back when next you reboot.