About USB memory stick with USB core + USB3300


Hello everyone,
I am developing software with using Cyclone5 now.
I have one question about USB memory.
With USB controller in HPS and USB3300 PHY chip, I found that there are two type about USB memory.
One is detected and the other is NOT detected.
Linux kernel version is 3.10-ltsi.

Please tell me how to distinguish the USB memory which isn’t recognized and a recognized USB memory.