Always-on-Display doesn't work

[MagneFire]

AsteroidOS relies on the HWcomposer 1.4 or 1.5 HAL API for Always-on-Display functionality. (in)harmony based watches have support for HWcomposer 1.4 but for some reason the screen still powers off after transitioning to ambient mode.

Currently, it seems that the blanking state of the display is controlled in two places, namely: mce (https://github.com/AsteroidOS/mce/blob/master/mce-fbdev.c#L276) and hwcomposer. This works fine for most devices, but on tetra I've observed that the blanking state shouldn't change when entering AOD mode. Something that we could try to do, is simply disable blanking from mce and let this be handled by the hwcomposer.

This might however not work as the Android base (that contains the hwcomposer) doesn't actually seem to have support for Always-on-Display functionality either. If this is the case then a set of patches are likely to be needed for the kernel to support this functionality. That's assuming that the hardware already supports this too.