HDMI output stopped - how to debug?

[skatopn]

I have noticed that the HDMI output seems to fail after the screen has gone to sleep or been power cycled.

I suspect this may have something to do with the HDMI protocol negotiations failing to reestablish trust (HDMI uses certificates or SSL I believe).

How can I debug this, or at least force the HDMI interface to renegotiate (bounce it)?

[bartjsmit]

I reckon EDID https://www.extron.com/article/uedid

You can keep the display output alive with a dummy plug and connect the monitor when you need it (hint: use SSH instead). Google "hdmi edid dummy plug"

Bart...

[skatopn]

Interesting. Might give it a go. Thanks!

[Greg_E]

I'm going to guess that you have more than 1 video connection available and it is defaulting to the other connections. If you connect to output 1 it might not do this. That said it might also be in BIOS.

My HP T740 does not do this, but I have a display port to VGA adapter on port 1, but my KVM switch might also handle the dummy duties too.