By -n I assume you were talking about -ndevs (list all devices), but you lost me with --dev... Searched high and low and could not find it. Mind pointing me in the right direction?
Typo on my end. Here is the correct parameter, --usb, used like so:
pi@raspberrypi:~/git/vthoang/cgminer $ ./cgminer -n
[2017-03-27 06:47:38.562] USB all: found 7 devices - listing known devices
.USB dev 0: Bus 5 Device 64 ID: 10c4:ea60
Manufacturer: 'GekkoScience'
Product: '2Pac BM1384 Bitcoin Miner'
[2017-03-27 06:47:38.562] 1 known USB devices
pi@raspberrypi:~/git/vthoang/cgminer $ ./cgminer -o stratum+tcp://solo.ckpool.org:3333 -u 1BURGERAXHH6Yi6LRybRJK7ybEm5m5HwTr -p x --suggest-diff 32 --gekko-2pac-freq 150 --usb 5:64
I know about --usb param. Unfortunately that does not help if device needs to be unplugged/plugged. It'll come up at different USB and then you need to restart cgminer and wait for diff to come down to a reasonable level...