MPU-9250 synchronization with Camera

I use MPU-9250 with Motion driver v5.1.3. and I have to use it with Camera in my application. It is important that camera frame and sensor readings frame from MPU is taken at same time. I am wondering is it possible to use DMP and make good synchronization with external device as camera in my case?
It is not clear from documentation how is this done. I see that there is FSYNC pin and there is 26. Configuration register where is option for enabling FSYNC pin for gyro or accel axes data sampling. I don't understand why is there option for every axis separately, I want to sample all axes from gyro and accel at same time and if possible receive gravity data from DMP.