Do not start the jetson tx2 developer kit without a connected monitor

Do not start the jetson tx2 developer kit without a connected monitor.
I connect the monitor with a black screen, no signal. Restart the board with the connected monitor, start up. But it does not always start, sometimes you need to turn off the power supply. Only after that will start. What could be the problem?

Just something to think about prior to debugging: HDMI is “hot plug”. Thus a “connect” or “disconnect” event triggers an attempt to configure. In the case of a Jetson this implies reading the EDID data from the monitor…if you have an old style VGA anywhere in the line this will cause EDID to fail. For other issues the moment of detecting the monitor may differ, and thus the result of any bug may also differ (example: if there were a bug in coming back from sleep the trigger might be doing something different than a monitor right after boot; or a disconnect/reconnect on a running system might inadvertently change something).

So before anything can be determined you’ll need to give exact details of monitor cable type, including any adapters. You will also want to mention which L4T version is in use. See:

head -n 1 /etc/nv_tegra_release

Here is a URL on video debugging:

In particular, if you want to verify that the system has been able to read the data which is mandatory for a successful automatic configuration, verify that hex data shows up here:

sudo -s
cat `find /sys -name edid`

Do note that unlike a desktop PC not all modes are supported. Modes must be from a mode pool in the driver. See that URL’s “ModeDebug” comment if you want verbose mode pool logs.

Note that because HDMI is hot plug that there may be times when unplug/replug helps or hurts…it just depends on what is going on. In theory, if everything were perfect, then there would be no difference and any plugged in monitor would always work.


Any update?