I posted this question first on StackOverflow. I got the hint to post it here with additional information. So here is the updated question.
I tried to connect a usb webcam directly to my computer running linux. However the webcam doesn't get detectet. If I run lsusb there are only the "Linux Foundation root hub" things showing up but no device. Just to test I connected a passive usb hub with 4 ports to my computer and connected the webcam to the hub. Surprisingly the webcam shows up in lsusb.
Why does my computer only detect the webcam through a passive usb hub and not directly? Where is the difference and how to probably fix this issue?
It's a usb 2.0 hub with usb 2.0 webcam connected.
lsusb output when the webcam is connected through hub to computer:
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 003: ID 046d:082b Logitech, Inc. Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
lsusb output when the webcam is connected directly to computer:
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
dmesg doesn't show something special when the webcam is connected directly to the computer.
Additional information #2:
If I connect the webcam directly to the computer it stays stable. But if I connect the webcam through the passive usb hub the computer shuts down (obviously because it draws to much power for a moment). But after the computer booted up again, it shows my webcam.
The "computer" is a C.H.I.P. from Next Thing Co. with only one usb port. I control it headless via ssh terminal.