No signal on composite (aka cvbs) output

[tllim]

After googling aroung, I've checked the /sys/class/drm directory. So here is just HDMI-1:

root@rock64:~# cd /sys/class/drm/
root@rock64:/sys/class/drm# ll
total 0
drwxr-xr-x  2 root root    0 Jul 15 17:51 .
drwxr-xr-x 64 root root    0 Jul 15 17:51 ..
lrwxrwxrwx  1 root root    0 Jul 15 17:51 card0 -> ../../devices/platform/display-subsystem/drm/card0
lrwxrwxrwx  1 root root    0 Jul 15 17:51 card0-HDMI-A-1 -> ../../devices/platform/display-subsystem/drm/card0/card0-HDMI-A-1
lrwxrwxrwx  1 root root    0 Jul 15 17:51 controlD64 -> ../../devices/platform/display-subsystem/drm/controlD64
lrwxrwxrwx  1 root root    0 Jul 15 17:51 renderD128 -> ../../devices/platform/display-subsystem/drm/renderD128
-r--r--r--  1 root root 4096 Jul 15 17:51 version
root@rock64:/sys/class/drm#

So, I think here is my problem, here should be "card0-Composite-1" or something like that... It looks like Rock64 didn't recognize CVBS output...

Any ideas?

If both HDMI and CVBS plug in at the same time, I thinks the video route to HDMI output. Just unplug the HDMI cable form ROCK64 board and keep the AV cable plugin,  there may be CVBS output.