HDMI TV blanking on and off at 120hz only

Issues & Assistance
1

Hi all, I am having a weird issue with what I think is either with my GPU drivers, Wayland, or a combo of both.

I have an Radeon 9070XT plugged via HDMI to a 4K 120Hz Samsung TV with VRR, and then a normal monitor via Displayport, 60hz no VRR. Whenever I set my TV to 120hz refresh, it starts to blink on and off randomly like its losing signal or trying to set some configuration and failing. If I set it to 100hz or lower it works fine. The displayport screen has no issues.

This happens both in Wayland GNOME and KDE Plasma 6.3 and 6.4 beta, but doesnt happen in X11 or Windows 11. I have the TVs config set to no adaptive sync and ‘prefer efficiency’ for color accuracy. Im on whatever the latest mesa drivers are for CachyOS

I’m not too familiar with Wayland troubleshooting. Can someone point me to a logfile I can look at? dmesg and syslog dont show anything when the TV blinks off and on.

Here is the bug report:

Much appreciated.
-Terrik

2

Believe it is a HDMI 2.1 problem. I don’t think AMD GPUs can do 2.1 because the HDMI forum wouldn’t let them open source a driver for it.

3

Interesting. I just started reading up on that and it sounds like that could be the culprit.

I just ordered an HDMI to DP cable that some reddit posters say might work, sounds like VRR might be an issue though.

I’ll have to tinker around a bit and see which feature I can live without to stay under the 2.1 bandwidth limit.

Thanks!