"Unsupported resolution" on screen - force a particular resolution?

Hey, I’ve just gone through the instructions to get a rootfs system with Nouveau drivers going, and it’s booting ok, but now the screen I’m using isn’t working on boot. Is there a way (either by editing a config file or through the uboot console) to force an output resolution through the HDMI?

Regardless of driver, I assume you are using X11 for graphics display. Jetson is configurable like any other Ubuntu linux (web documents on Ubuntu are valid for Jetson). Typically this means editing /etc/X11/xorg.conf. This file has a “Monitor” section which is mostly blank on Jetson because (like most modern linux distributions) it uses the query of the monitor itself for information about the monitor. This is the DDC pin available on most all modern video connectors (this is absent on VGA…if you use any kind of VGA cable this would account for failed video). The information is the DDC or EDID information.

The application “get-edid” can read the EDID data from the DDC channel. To be useful it must be piped through either one of two other applications. Package “read-edid” provides “get-edid” along with one of the other applications, “parse-edid”. Although you might find the second application “edid-decode” of interest you won’t need it for this purpose (if you want to use it the package is “edid-decode”. The use which helps you in your case is this:

get-edid | parse-edid

Assuming you have DDC/EDID channel available your system should be able to take advantage of this information and function correctly. Since this is not happening I assume either your cable has some form of VGA adapter or else some other failure of DDC/EDID. If your cables do not have VGA adapters you can test the automated information via the above listed command. If this command does not show output for your monitor then you can put this monitor on another linux machine which has this working and use the “Monitor” section output from the command to directly paste into xorg.conf and replace the old “Monitor” section. Otherwise you will need to figure out by hand what goes into that “Monitor” section to get it working.

Thanks for your reply! Actually, I’m not using X11. I’ve been following these instructions to get Wayland + Weston running: https://github.com/NVIDIA/tegra-nouveau-rootfs

Weirdly, the basic console doesn’t even display (before even trying to start Weston), so I can only SSH/serial in. Here’s the serial log from a bootup: https://gist.github.com/geelen/ffb625655e84a2f28e1b

The standard L4T 21.2 image works fine with the monitor, so I’ll use that technique to get the EDID info I need, thanks, but now I have no idea where to put it :)