title: Cannot open /dev/video0 (No such device)
body: <p>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):</p>
  
  <pre><code>[  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
  </code></pre>
  
  <p>This is the lsusb output:</p>
  
  <pre><code># 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
  </code></pre>
  
  <p>However, I cannot access the camera:</p>
  
  <pre><code># v4l2-ctl --all 
  Failed to open /dev/video0: No such device
  </code></pre>
  
  <p>in strace:</p>
  
  <pre><code>open("/dev/video0", O_RDWR)             = -1 ENODEV (No such device)
  </code></pre>
  
  <p>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...</p>
  
  <pre><code>crw-rw-rw- 1 root video 81, 0 Jun 14 12:07 /dev/video0
  </code></pre>
  
  <p>lsmod shows that uvcvideo is not used for the camera:</p>
  
  <pre><code># 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
  </code></pre>
  
  <p>Any ideas?</p>