How to force a resolution/modeline on TX2 platform?

I have tried every Xorg configuration I could think of but nothing is working. I have even had xrandr run directly from lightdm on startup (display-startup-script etc.) but that sets the modeline and then X resets it (my guess is nvidia driver is doing something wonky here).

What is the proper way to FORCE a resolution on the TX2 because none of the standard ways are working. The only way I can do it is MANUALLY log in and run xrandr after X has started.

Has anyone else seen this problem before? It is so strange.

I’m on 28.2 (16.04 run-time).

Btw, I mean AFTER X has fully started I can do this:

DISPLAY=:0 xrandr --output HDMI-0 --mode 800x480 --rate 60

This works. But if I execute this on startup (either via .xprofile or lightdm), it looks like the Tegra driver immediately sets it back:

[ 16.432] (II) NVIDIA(0): Setting mode “HDMI-0: 800x480_60 @800x480 +0+0 {ViewPortIn=800x480, ViewPortOut=800x480+0+0}”

[ 17.483] (II) NVIDIA(0): Setting mode “NULL”
[ 17.588] (II) NVIDIA(0): Setting mode “HDMI-0: 1280x720_50 @1280x720 +0+0 {ViewPortIn=1280x720, ViewPortOut=1280x720+0+0}”
[ 18.866] (–) NVIDIA(GPU-0): Daewoo HDMI (DFP-0): connected
[ 18.866] (–) NVIDIA(GPU-0): Daewoo HDMI (DFP-0): External TMDS
[ 19.946] (–) NVIDIA(GPU-0): Daewoo HDMI (DFP-0): connected

xorg config seems to be ignored too. This only happens on Tegra.