I’ve never set up DSI, so I can’t offer any advice specific to this. Assuming the device has become available, I’d assume the next step would require proper configuration of the X11 server. Understand that the EDID data line of HDMI provides information to the video system in a standard format used for automated configuration…your DSI must either provide EDID data this way as well, or else the configuration would require manually adding the information to the “/etc/xorg.conf” file by hand (an exception would be if the default mode just happens to work with the particular display). Does the DSI have EDID (I am not familiar with DSI wiring)?
Incidentally, packages “read-edid” and “edid-decode” may be of use in showing what the system sees:
sudo get-edid | parse-edid
sudo get-edid | edid-decode
Additionally, raw EDID data can be seen in a TX1 for the HDMI via:
# See edid files:
find /sys/kernel/debug -name 'edid'
# See content of edid files:
sudo cat `find /sys/kernel/debug -name 'edid'`
Note that for a default JTX1 with just a single HDMI display the file path in “/sys” is:
The “tegradc.1” might change depending on display when there is more than one display.