I have an AMD RX 6800 XT graphics card and am running openSUSE Tumbleweed. My
monitor is an HP Omen 27i, which supports Freesync, connected via Displayport.
The monitor's OSD indicates that adaptive sync is enabled. I am using the
amdgpu driver and an X11 Plasma 5 session. My refresh rate is 165 Hz. This is
my only monitor.

I cannot seem to get Freesync to work via the standard procedures, as verified
by my monitor's OSD framerate always reading 165, even in VRRTest or running a
game in fullscreen with the FPS capped below 165, and seeing the choppiness in
VRRTest. I have confirmed that the compositor is disabled while doing these.

This exact setup worked with my AMD RX 580. In fact, I've turned off the
computer, plugged the RX 580 back in, rebooted, and it works. It's not a
hardware problem, as I've tested live images of Kubuntu 21.04, Fedora 34's KDE
Spin, and Manjaro, and all worked fine by creating the appropriate amdgpu.conf
file and logging out and in. I can't, however, get it working with an openSUSE
Tumbleweed live image by following the steps below plus installing the
xf86-amdgpu driver and rebooting.

Weirdly, I can get VRR to work by logging into a Sway session, where VRR works
wonderfully, logging out, and logging into Plasma 5 X11. This doesn't persist
through a reboot, and it seems buggy while doing this. E.g., when dragging a
window, everything is a smooth 165 FPS, but when just moving the mouse, it sits
at a very choppy 48 Hz, which is the lower limit of the Freesync range on this
monitor.

Steps to reproduce:

0) Obtain compatible hardware setup: One monitor, Freesync enabled, connected
by Displayport; AMD 6800 XT graphics card.

1) Create /etc/X11/xorg.conf.d/20-amdgpu.conf file:

Section "Device"  
     Identifier "AMD"  
     Driver "amdgpu"  
     Option "TearFree" "true"  
     Option "VariableRefresh" "true"  
EndSection  

(I've tried removing the TearFree option and it doesn't solve the problem.)

2) Log out and in. Freesync should now be enabled, but it doesn't work.

Additional info:

Running xrandr --props shows vrr_capable 1.

/var/log/Xorg.0.log contains the lines

[     8.124] (**) AMDGPU(0): Option "VariableRefresh" "true"

and

[     8.211] (**) AMDGPU(0): VariableRefresh: enabled

It seems like everything is correct, but Freesync isn't working.

I first verified this problem on Mesa 20.3.4-272.4 and Kernel 5.11.4-1-default.
I am now on kernel 5.11.6-1.2. No updates are available. I don't have any wacky
repositories that should be causing problems.

I know this may be difficult to replicate given hardware availability. If I can
help, let me know. I no longer have possession of the RX 580.