Huawei P8 phones like GRA-L09, GRA-CL00, GRA-UL00, GRA-UL10 etc don't need root, just install Boldbeast Recorder V8.0 or newer versions and go, it records calls very well in two directions.
Please use these settings to record calls:
- Record Mode: 5
- Record Format: WAV
- File Sample Rate: test 8000, 16000 and 32000
- Tune Audio Route: Group3