Installing an actual Sailfish OS on an FP2 requires the flashing of an outdated “firmware” (June 2016) into the modem partition for mitigating battery drain and “search for bluetooth devices reboots”.
(The “modem firmware” is AFAIK actually a separate OS for the SoC controlling not only the “radio” part, but all sensors, WiFi, BT, USB etc.)
Can someone explain the technical reason behind this?
I did some testing with my latest build using backported Bluetooth kernel drivers with bluez5 and the kernel panics related to Bluetooth do not seem to happen anymore with modem partition from FP OpenOS 18.03.1. Not sure if the change is because of bluez5 and/or backported drivers or possible changes in firmware.
This leaves us with only the battery drain issue in Sailfish OS when using latest modem partition. The reason for the battery drain is that something in the firmware or android side vendor libraries is preventing Sailfish OS from going to sleep when idle, possibly due to continuous interrupts or something similar.
It should be possible to work around the issue by implementing a native kernel driver for the proximity sensor. I have already partially implemented the needed driver but need to finish and test it properly.