Cannot open /dev/video0 (No such device)

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I am trying to install a webcam on a Synology NAS (arm, linux kernel 3.2.40). I have compiled and installed the kernel modules, they seem to work. This is the kernel output when inserting the modules and plugging the camera (Logitech C270):

[  130.963903] Linux video capture interface: v2.00
[  136.098356] usbcore: registered new interface driver uvcvideo
[  136.104135] USB Video Class driver (1.1.1)
[  145.384393] usb 3-2: new high-speed USB device number 4 using etxhci_hcd_150119
[  145.628583] uvcvideo: Found UVC 1.00 device USBDevice (046d:0825)
[  145.726156] input: USBDevice as /devices/pci0000:00/0000:00:00.0/usb3/3-2/3-2:1.0/input/input0

This is the lsusb output:

# lsusb 
libudev: udev_has_devtmpfs: name_to_handle_at on /dev: Function not implemented
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 004: ID 046d:0825 Logitech, Inc. Webcam C270
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

However, I cannot access the camera:

# v4l2-ctl --all 
Failed to open /dev/video0: No such device

in strace:

open("/dev/video0", O_RDWR)             = -1 ENODEV (No such device)

I have tried different camera model, the C270 on another computer (works fine), deleting /dev/video0 and re-creating it (mknod /dev/video0 c 81 0), changing permissions, etc. but I get the same error...

crw-rw-rw- 1 root video 81, 0 Jun 14 12:07 /dev/video0

lsmod shows that uvcvideo is not used for the camera:

# lsmod 
Module                  Size  Used by
uvcvideo               57657  0 
videodev               72561  1 uvcvideo
usbcore               147080  7 ehci_hcd,etxhci_hcd,usb_storage,usblp,usbhid,uvcvideo
usb_common               592  1 usbcore

Any ideas?

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