I am building an openwrt image for Raspberry Pi 3B+ and other variants.
I updated to latest 22.0.3 tag and rebuilt my image and now I get an error when accessing GPIOs via libgpiod.
If I run gpiodetect or gpioinfo they don't return any controller.
I see that libgpiod doesn't use the sysfs interface anymore and I don't have /dev/gpiochip0 device.
Running gpiodetect returns and empty list.
But if I check under /sys the controller seem to be recognized:
# ls /sys/class/gpio/ export gpiochip0 gpiochip504 unexport
In my kernel config I have CONFIG_LIBGPIOD selected.
If I check /proc/devices gpiochip is there:
# cat /proc/devices Character devices: 1 mem ... 254 gpiochip
But if I try to manually create /dev/gpiochip0 using mknod:
# mknod /dev/gpiochip0 c 254 0
then gpiodetect returns an error:
# gpiodetect gpiodetect: unable to access GPIO chips: No such device or address
The same application/configuration worked with 21.x.
What else should I check to understand what's going wrong with my device?
I haven't changed the dts files and, anyway, if the device is reported under /sys/ I suppose it has been correctly detected and configured.
Isn't mknod enough to create a new device entry for gpio?
Are there some other kernel configs that should be enabled to activate the character device interface for GPIOs?
TY for any help you may provide.