I have a simple Ikling USB-C dock. Upon going into screen blank power saving, a wake-up is immediately triggered. It seems to be coming from the dock HDMI interface. I can’t figure out how to debug wake event signals, and it’s not clear the difference been suspend wakeup and screen blank wakeup. This is what I see in the system log:
audit: BPF prog-id=0 op=UNLOAD
audit: BPF prog-id=0 op=UNLOAD
kernel: [drm] DP Alt mode state on HPD: 1
audit: BPF prog-id=137 op=LOAD
audit: BPF prog-id=138 op=LOAD
Most of the time if related to immediately wake up is cat /proc/acpi/wakeup and the solution most of them are disabling one or some devices listed in that configuration by using script that executed on start up.
I have tried disabling every wakeup=enabled in /sys and no luck. My only clue remains “kernel: [drm] DP Alt mode state on HPD: 1” and it seems like going to sleep is triggering the SUB-C dock to reset and the system detects is as a new monitor getting plugged in, which then causes Xorg to reset and go back to an active screen.
The device is a bit odd in that is has audio-out jack, but not connected to USB, rather it diverts audio coming in from the DPMS signal. This mechanism may be doing weird things to the DPMS signal to cause a flicker in sensing of a monitor being present.
The only thing I can think of now is, maybe I can configure the X layout to be fixed and not auto-detected.