If you compare the device tree as loaded by Linux, available in /sys/firmware/fdt, you will see that it differs from the one that you loaded in U-Boot. Taking the time to make the comparison is quite instructive.

Let’s do this on my Toradex Verdin iMX8M Mini SoM on the Dahlia carrier board.

Decompiling the DTB

It’s easy to decompile any Device Tree Binary (DTB) file using dtc, the Device Tree Compiler.

1. Copy /sys/firmware/fdt from your live Linux system to external storage (assuming your external storage is mounted on /mnt/usb)
   cp /sys/firmware/fdt /mnt/usb/linux.dtb