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I've connected a Logitech c170 webcam to a Raspberry Pi via an externally powered USB hub. It's running Raspbian Wheezy.

The camera is detected by the Pi when plugged in, and running VLC even causes the light on the camera to turn on. However, no image is displayed. I tried to grab an image using streamer and got the following output

files / video: JPEG (JFIF) / audio: none
libv4l2: error allocating conversion buffer
mmap: Cannot allocate memory
v4l2: ioctl(fildes = 3 "/dev/video0", request = VIDIOC_QBUF, struct v4l2_buffer *data = { index = 0, type = 0, bytesused = 0, flags = 0, field = V4L2_FIELD_ANY, timestamp = { 0 seconds }, timecode = { type = 0, flags = 0, frames = 0, seconds = 0, minutes = 0, hours = 0 }, sequence = 0, memory = 0, length = 0, input = 0 }) failed, Invalid argument (22, EINVAL) because the data->type argument was incorrectly specified
v4l2: oops: select timeout

And when I killed the program this error was printed many times

munmap: Invalid argument

Is there a driver missing?

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Results with webcams (and USB devices in general) vary widely from one firmware rev to the next. Can you give us a "uname -a" ? –  Tai Viinikka May 11 '13 at 1:23
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