No, no - I have obviously everything working in DTS because it works when plugged in to Nvidia Devkit. I have disabled the HDMI and tried with DisplayPort enabled and disabled.
We connected DSI panel to Nvidia Devkit just by soldering tiny wires directly from DDR4 connector on the devkit to the display. I mean literally everything works as intended on Nvidia Devkit. This is not a question on how to bring up DSI display but about this Tegra tegradc driver
I found this article: TX2i tegra_nvdisp_head_enable fails if HDMI is connected after boot - #7 by richardsearle
Could it be that EVEN if the HDMI and DisplayPort is disabled in device tree, Nvidia Jetson checks for HPD DP and HDMI pins? They are left floating in our board.