Looking back through boot logs this message is seen on all kernels used
on this Asus T300CHI, from v4.15 onwards:
hidraw: raw HID events driver (C) Jiri Kosina
i2c_hid i2c-INVN6500:00: i2c-INVN6500:00 supply vdd not found, using
dummy regulator
i2c_hid i2c-INVN6500:00: Linked as a consumer to regulator.0
i2c_hid i2c-INVN6500:00: i2c-INVN6500:00 supply vddl not found, using
dummy regulator
i2c_hid i2c-INVN6500:00: unexpected HID descriptor bcdVersion (0xca9b)
inv-mpu6050-i2c i2c-INVN6500:00: mounting matrix not found: using
identity...
inv-mpu6050-i2c i2c-INVN6500:00: i2c-INVN6500:00 supply vddio not found,
using dummy regulator
It's not clear if this is a warning that can be disregarded or an
indication the protocol isn't being completely decoded.
The accelerometer is working correctly but the ambient light sensor
isn't. I tested that by shining an LED camera light around the edges of
the device where the sensors are located and monitoring for changes.
I'm reasonably sure the light-sensor has worked previously but it isn't
something I would generally notice since the device is used in fairly
constant low-light conditions.
This may or may not be related to the error message.
$ monitor-sensor
Waiting for iio-sensor-proxy to appear
+++ iio-sensor-proxy appeared
=== Has accelerometer (orientation: normal)
=== Has ambient light sensor (value: 0.000000, unit: lux)
