Make does not find "tegra-gpio.h"

On av very clean install of L4T 21.2, the make suddenly fails while compiling the dts files. The message is

arch/arm/boot/dts/tegra124.dtsi:1:41: fatal error: dt-bindings/gpio/tegra-gpio.h: No such file or directory

Actualy, the zImage file is ok, so it does not matter much. It happend when I edited the dts file tegra124-jetson_tk1-pm375-000-c00-00.dts which I manualy compile it into its dtb file.
The file tegra-gpio.h does exist in two places, both identical.


Why does not the dts/dtb compiler find it?

I’m not set up for 21.2, but such things are very common if the initial configuration is not valid. Where was your starting .config from?

I found the problem at last. It was a missing symbolic link. Includes are taken from arch/arm/boot/dts/include. This directory contains only a symbolic link to …/…/…/…/…/include/dt-bindings.
This symbolic link had been converted to an ordinary text file for some reason, and the “git status” command did no detect the difference, so even a git --force checkout master did not fix the problem.