Some devices (like some / most Sony phones) have problems with proximity sensor if the sensor is kept constantly enabled. Typically it gets stuck in some state, which then makes e.g. at-ear blanking during calls misbehave.
As a workaround for these devices utilize “on-demand” proximity sensor mode. Unfortunately this then means that lpm / glance / sneak peek mode does not really work as it requires constantly up to date proximity sensor state.
Now, it looks like C2 too does not like to have its p-sensor constantly powered on, but fortunately C2 also has support for some android wake up / pick up / glance type sensors. One of these can be used for waking up the device to lpm when display is off and proximity sensor disabled.
Basically that devices with on-demand-ps + wakeup-sensor work almost like devices with p-sensor that can be constantly powered on. Most notable difference being: how do you make device that is lying on table show date and time in lpm? By picking the phone in hand, or by waving hand above the sensor area.
Also: in lpm double tap works without touch panel hw / drivers supporting double tap wakeups. So, having phone go to lpm when it is picked up / taken from pocket somewhat remedies lack of real double tap support too.
Note that you also need sensorfw-qt >= 0.15.0 (and depending on device type also hybris-libsensorfw-qt5-hal or hybris-libsensorfw-qt5-binder package).
What I’ve used to enable this on C2 is:
mcetool\
--set-wakeup-sensor-mode=enabled\
--set-low-power-mode=enabled\
--set-ps-on-demand=enable\
--set-lpmui-triggering=from-pocket,hover-over\
--set-doubletap-mode=unlock