I am experiencing an HDMI output issue on my Radxa board (radxa-a733_bullseye_kde_r4.output_512.img)

Cubie Series A7S
1

Hello Radxa team,

I am experiencing an HDMI output issue on my Radxa board (radxa-a733_bullseye_kde_r4.output_512.img).

The board recognizes the HDMI connection — the connector appears as DP-1 (connected) in the DRM subsystem — however, there is no actual video output on the HDMI monitor.

Steps to reproduce:

  1. Connect HDMI monitor to the board
  2. Check DRM connector: ls /sys/class/drm/ shows DP-1 as connected
  3. Monitor receives no signal

Additional info:

  • The DRM driver is sunxi-drm
  • SDDM display manager was disabled to free the DRM device
  • Attempted output via FFmpeg fbdev and mpv --vo=drm --drm-connector=DP-1, but no signal on monitor

Could you please advise on what may be causing the HDMI signal to not reach the monitor despite the connector showing as connected?

Thank you.