Using the Generic Timestamp Engine to get timestamp for each frame from CSI-2 input

Hi sir,

I have a frame valid signal from Camera. On each frame, this signal generate a pulse.
I would like to use GPIO ISR as timestamp for each frame.

How can I use the Generic Timestamp Engine to get timestamp for each CSI-2 RX frame?
How about the latency from GPIO ISR to stamp done?

Br,

Yuki