Wednesday, June 29, 2016

XT1064 Android 6.0 will not go into deep sleep, CPU stuck awake

I have a Moto G 2014 (XT1064) running Android 6.0 that will not go into deep sleep. I could see that the CPU was never going into the deep sleep state even when the phone was not being used and no user apps were actively running in the background. This is causing abysmal battery life as expected. The phone was updated to Android 6.0 via regular OTA updates. I haven't flashed any third party ROMs onto it at all since I bought it.

The first thing I did to investigate was to unlock the bootloader (it was still locked since purchase prior to this) so that I could obtain root access to see what was going on. This also had the additional affect of wiping the phone to stock Andoird 6.0, which I had hoped would maybe solve the problem but it did not.

My first thought was that it was a user app that was holding a wakelock keeping the phone awake. I looked at the user and kernel wakelock counts via BetterBatteryStats and WakeLockDetector, but from what I can tell it is not any user app that is holding a wakelock at all. Instead it must be some kernel level app keeping the CPU awake, but I can't determine what it is. There isn't any single entry in the wakelock list that sticks out as the culprit.

I have done some other investigative tests such as turning WiFi off while the phone sits unused overnight. This did not have any effect as the phone still remained awake the whole time. I also repeated this test with the phone in airplane mode (WiFi + cellular radios off) and again it had no affect. From this I could only conclude that it was not the wireless radios that were keeping the phone awake. The wakelock counts also didn't show any evidence that WiFi, cellular or GPS were holding wakelocks.

Here are two screenshots I took of the BetterBatteryStats and WakeLockDetector apps showing the highest count kernel wakelocks over a roughly 17 hour period:
(I'd link them in properly but I am prevented from posting outside links on this forum until I have 10 cumulative posts...)
http://ift.tt/2947LCq
http://ift.tt/294QzJp

You can see that the phone has been awake 96% of the time during this period, and that the highest count kernel wakelocks are from "event8-1877", "event9-1877", "qpnp_soc_wake" and "qpnp-vadc-e4a28400". I could not find any information as to what these entries mean or what they're related to. Whatever they are, they appear to have abnormally large wakelock counts which leads me to believe that they are related to this problem. The other thing that puzzles me is that the total time for the top four entries in that list only sum to about 2 hours, yet the phone has been awake for almost 17 hours within the same period.

If anyone has any idea about this I'd appreciate the help. I may be completely wrong about the root cause here but I'm running out of ways to debug this.


from xda-developers http://ift.tt/2947uzr
via IFTTT

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