A problem with the stable GPS fix

[Andrey]

I'm using Samsung Galaxy S4 mini (serranoltexx) running LineageOS 14.1 since 2018. Some time ago I'm experiencing such a strange problem with GPS fix. GPS chip can find satellites quickly with a strong signal (4 and more satellites) but can't get stable GPS fix. It may get GPS fix for a few seconds and then I need to wait again for the next GPS fix. It means that GPS fix is unstable. I can see the same behavior in any app for example gpstest.

Could you please give me advice how to troubleshoot this issue with the poor GPS fix?

In the logcat I can see the following entries after the GPS fix is losing:

04-17 21:32:48.092   598  1063 E LocSvc_ApiV02: W/virtual int LocApiV02::setGpsLock(unsigned int):3033]: Set engine lock failed. status: eLOC_CLIENT_SUCCESS, ind status:eQMI_LOC_ENGINE_BUSY_V02
04-17 21:34:08.358   598  1063 E LocSvc_ApiV02: W/virtual int LocApiV02::setGpsLock(unsigned int):3033]: Set engine lock failed. status: eLOC_CLIENT_FAILURE_INVALID_PARAMETER, ind status:eQMI_LOC_SUCCESS_V02

I'm tying to understand if this problem is related to the software defect i.e. LineageOS 14.1 or to the hardware - maybe GPS chip is almost dead. Also tried to Google these but no luck. I would not like to change the phone with no reason because it's very compact and handy. Thank you in advance.

P.S.: I have opened the same subject on XDA because the original LineageOS developer is still there.

[Sean Barbeau]

My guess is that there is a mismatch between the GNSS drivers and hardware - the "invalid parameter" likely means that the higher level software is trying to pass data to the lower level software that it doesn't understand. This is a common issue with ROMs where often drivers are ported from one device to another, without an official release from an OEM for that particular hardware. Android 7 and higher got significantly more complex in the area of GNSS interfaces with the hardware with the addition of raw measurements, etc.

So you might try reverting to an older LineageOS version if it previously worked. Otherwise, aside from an update to LineageOS, I'm not sure there is much you can do.

Sean

[Andrey]

My test results are inconsistent. But I found that putting the device in the airplane mode helps to obtain a stable GPS fix. When turning off the airplane mode GPS fix is losing immediately. I did it a few time and the results were very stable. Then I have replaced the SIM card and found that this problem is not reproducible anymore i.e. GPS fix is  stable in both modes normal and airplane. Finally I put back the initial SIM card back and also can't reproduce the problem. I have an assumption maybe this is somehow related to the power fluctuation. My SIM card is 3 years old. Once the problem will come back I will try to play with the airplane mode again and if the test will be consistent maybe I will need to replace the SIM card by a new one.