I am using a carrier board designed for TX2. (no devkit EV board, board with DP port added)
The dts file I used was “tegra186-quill-p3310-1000-c03-00-dsi-hdmi-dp.dts” and enabled the DP port.
However, when using nvpmodel 0 (CPU 2GHz, GPU 1.3GHz with Cooler on) to use the full performance of the system, it sometimes happens that CPU gets locked or Ubuntu skin is broken.
It seems as if the memory arbitor is not scheduling properly due to a lack of bandwidth.
This phenomenon did not occur in Jetpack 3.2 (4.4.38 tegra kernel: same usage condition).
Have you made any special changes to Jetpack 4.2?
Symptom is reproducible when both HDMI and DP are connected.