We have noticed some problematically large latency in the TX1 V4L stack, and am wondering if you might be able to shed some light on where the issues may be coming from.
We are seeing ~66ms of latency in the camera stream, and believe that it is related to something in the TX1 driver stack because we have tested 3 different configurations with the same cameras:
- MIPI data directly into the TX1 results ~66ms of latency
- MIPI data into the TX1 via USB (using a MIPI to USB converter) results in ~66ms of latency
- MIPI data into Intel CPU via USB (using a MIPI to USB converter) results in ~8ms of latency
The hardware is the same for all of them, except for the MIPI to USB converter which is the same for 2 and 3. We used the same user space driver code for all 3 experiments.
The images are streaming in at 15FPS, so the frame period is suspiciously close to the latency number.
Is there some buffering happening that would make it so that images are not released to user space until the next image arrives?