[tde-users] Greeter on wrong display

I have a PC with 2560x1440 on DisplayPort, and 1920x1080 on HDMI. The greeter shows up on the small HDMI screen. Is there something in tdmrc or friends that can move it to the DP screen, and preferably, start off TDE sessions by default with the larger/DP screen as the primary? I know how to use xrandr to make the DP primary, but it's not working for the login greeter. It tried it in /etc/trinity/tdm/Xsetup, but it's apparently ignored or otherwise ineffective there.