April 2016: I now advocate a different approach to solving this problem – see my update at https://vaughanharper.com/2016/04/28/solution-to-an-hdmi-problem-v2/ .
I recently got a Marantz AV receiver, but I had an annoying problem connecting my MythTV system to the television through it: things are fine if, when I boot up the MythTV system, the TV is switched on and the MythTV input selected on the receiver – but if after that I select a different input on the receiver, then when I switch back after a period of time it doesn’t reconnect, and just displays a blank screen. (This was on Ubuntu 14.04; I was using an Intel graphics chip, a Gigabyte GA-H55M-UD2H motherboard and a Samsung television.)
Fortunately various other people have had the same problem and I found this reference:
It turns out that xsettingsd is causing the problem – if it’s running it causes the TV to come up in a NULL mode, but if it’s killed, the TV remains in the mode it was previously running in. (In spite of the title, the item applies to non-NVIDIA graphics hardware as well.)
The suggested workaround was to add the following in /etc/mythtv/session-settings:
I tried this out and thankfully it did indeed solve the problem!