I have a Thinkpad X1 Tablet (gen 2) with a front and back integrated camera running Ubuntu 19:10. The cameras appear to be detected:
v4l2 device info [/dev/video0]
general info VIDIOC_QUERYCAP driver : "ipu3-cio2" card : "Intel IPU3 CIO2" bus_info : "PCI:0000:00:14.3" version : 5.3.18 capabilities : 0x84201000 [?,?,STREAMING,(null)]
inputs VIDIOC_ENUMINPUT(0) index : 0 name : "camera" type : CAMERA audioset : 0 tuner : 0 std : 0x0  status : 0x0 
When I start cheese I have 4 cameras labeled "ipu3-imgu". When I run guvcview I have 10 devices labeled "ipu3-imgu" which the system puts at /dev/video0-9 and four devices labeled "Intel IPU3 CIO2" which are /dev/video10-13.
But none of these work. Does anyone have a laptop with this kind of camera running Linux?
Does anyone know of a resource on debugging this kind of camera in Linux?