The issue now appears resolved with hwe-18.04/4.18.0-13, /sys/bus/iio is
now present and the functionality has been restored.
Summary:
/sys/bus/iio appears to be missing on all the bionic 4.15.* kernel releases
(including 4.15.0-43) but is present on xenial 4.4 and cosmic 4.18 (at least as
of 4.
https://news.ycombinator.com/item?id=18711970
The sad state of being able to use Ubuntu on touch devices (hint: you
can't)
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1807250
So, apparently support for an entire bus class has been missing since
ubuntu bionic (18.04 LTS) was rele
