V4L2_CTRL_CLASS_USER
V4L2_CTRL_CLASS_MPEG
V4L2_CTRL_CLASS_CAMERA
V4L2_CTRL_CLASS_FM_TX
V4L2_CTRL_CLASS_FLASH
V4L2_CTRL_CLASS_JPEG
V4L2_CTRL_CLASS_IMAGE_SOURCE
V4L2_CTRL_CLASS_IMAGE_PROC
V4L2_CTRL_CLASS_FM_RX