Meaning of frame_length and coarse_time

Analyzing different MIPI sensor drivers (ov5693, imx185, …) I’ve come up with some terminology I can’t fully understand. I’ve seen that frame_length is related to the frame_rate, and coarse_time to the exposure time, but how? I’ve searched in the sensor datasheet and no clue about these terms. Moreover, why some sensors need 3 addresses for, let’s say, frame_length, while others need only 2? Any documentation where this is detailed?
I’ve read the Sensor Driver Programming Guide, but yet the explanations are too generic.

All of your questions is about the sensors behavior. You should consult to sensor vendor to get the detail information.