Frame drop on V4l2 interface R24.1

Hi there,

I have a problem on V4l2 interface of R24.1, I have a HDMI to CSI2 chip on TX1, and we have our own ioctl-based( not Gstreamer ) test routine to evaluate the performance, it stream out at 4k@30fps UYVY format, we always execute the max performance script before running our routine, it can achieve 4k@30fps without any problem when first setting “VIDIOC_STREAMON”, if I stop streaming by setting “VIDIOC_STREAMOFF” and then set back to on, I will never get 30FPS anymore, but 15FPS instead, I can bring it back to 30FPS by fully loading all the 4 CPUs( using load test command “stress” ), I have no idea why CPU draw back its performance, are there any methods to keep CPU running at maximum performance without dynamically change it’s load or frequency. thanks.

Kevin

This should help. http://elinux.org/Jetson/Performance#Maximizing_CPU_performance

I always run the MAX performance script, it seems that’s not the problem of CPU’s governor.

usaarizona, did you have that issue with previous firmware (e.g. 23.2), or is it unique to 24.1 ?

We have some problem on our old driver working with R23.2, right now we only test the current driver with R24.1, the answer should be also true since this problem seems to relate with driver.

usaarizona, how long is the vertical blanking time? I’m more familiar with 23.2, and looking at the vi2.c code, it needs to partially re-start the hardware every frame (kind of a one-shot config), so if the vertical blanking is too short, I imagine it could start dropping every other frame.