I have a Pixel C plugged to a PC. The device is properly recognized by the kernel:
[ 190.454979] usb 1-22.214.171.124: new high-speed USB device number 9 using ehci-pci [ 190.550564] usb 1-126.96.36.199: New USB device found, idVendor=18d1, idProduct=5203 [ 190.550574] usb 1-188.8.131.52: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [ 190.550579] usb 1-184.108.40.206: Product: Pixel C [ 190.550583] usb 1-220.127.116.11: Manufacturer: google [ 190.550588] usb 1-18.104.22.168: SerialNumber: 611900XXXX
First, if adb is started as normal user, I get:
List of devices attached 611900XXXX no permissions
If adb is started as root, I get (and I can shell into it):
List of devices attached 611900XXXX device
I don't have this problem on my Android 6.0.1 Nexus 5X.
Moreover, the Pixel C can appear as a PTP device and the Camera folder opens in nautilus. But I never get a standard folder if I chose MTP (File Transfer) connection. Nothing pops up. Again, I have no problem with a Nexus 5X Android 6.0.1 and I can get MTP even if adb is started as normal user.
The device runs latest Android 6.0.1 build ryu-mxc14g.
Something is different on Pixel C from Nexus.
I think the problem is in libmtp which has not been updated for the Pixel devices. I see some patches for Nexus (such as 0x18d1 / 0x4ee2) but there is nothing for 0x5203. That's most likely the problem.