I've got the MPU-9250 working but there seems to be some problem with the accelerometer. When the board is moving and then at rest, the values of the accelerometer don't go back to the "resting values" (ideally it would be (x, y, z) = (0,0,0)). To make this clear I attached the image "accelerometer.png".
For this image: between 1.5s to 3.2s I move the board, then leave it at rest for about 2 seconds and then I move it again for 1.7s and then I leave it at rest again.
After each time, the values at rest of the axes X Y Z are different. It is like the registers stop updating w