Some more notes for anyone else who tries to use this: I got the controls back, apparently, there's a kernel->userspace transfer or something going on with uvc type things.
You'll need the file from the The Imaging Source github above, you need uvcdyntrl installed, then run this:
uvcdynctrl -i data/uvc-extensions/tisEUVC.xml -d /dev/video1
It goes from this:
v4l2-ctl -d /dev/video1 -l
brightness (int) : min=0 max=255 step=1 default=12 value=12
gain (int) : min=4 max=63 step=1 default=16 value=36
exposure_absolute (int) : min=1 max=300000 step=1 default=127 value=127
focus_absolute (int) : min=0 max=1000 step=1 default=0 value=0
privacy (bool) : default=0 value=0
to this:
v4l2-ctl -d /dev/video1 -l
brightness (int) : min=0 max=255 step=1 default=12 value=12
gain (int) : min=4 max=63 step=1 default=16 value=36
trigger_global_reset_shutter (bool) : default=0 value=0
exposure_absolute (int) : min=1 max=300000 step=1 default=127 value=127
focus_absolute (int) : min=0 max=1000 step=1 default=0 value=0
privacy (bool) : default=0 value=0
trigger (bool) : default=0 value=0
software_trigger (button) :
gainr (int) : min=0 max=63 step=1 default=1 value=36
gaing (int) : min=0 max=63 step=1 default=1 value=36
gainb (int) : min=0 max=63 step=1 default=1 value=36
binning (int) : min=1 max=4 step=1 default=1 value=1
x_offset (int) : min=0 max=1794 step=2 default=0 value=0
y_offset (int) : min=0 max=1464 step=2 default=0 value=0
Of those:
Brightness does nothing that I can tell.
Binning breaks it.
Trigger of all types is are somewhat untested by me, though they seem related to the snapshot mode.
Focus does nothing.
Exposure Absolute is in 0.1ms intervals. (Up to 300000 = 30 seconds, which seems to work. (Haven't tried it a lot yet, that's based on the white as this thing's background that showed up on streaming about 30 seconds after!))
R/G/B gains do work. There's probably an ideal value... but that either takes a patient approach or is the thing that drives people mad trying to properly figure out.
Testing with an ETX-70, I can see a fair number of stars. Sadly I can see stars, but I start to sink in the mud, and I'm exhausted.