Device tree functionality is broken (BBB 3.8.13)

The devicetree overlays don’t seem to work. I follow the prescribed process:

root@beaglebone:~# dtc -O dtb -o Nicks-foo-bar-setup-00A0.dtbo -b 0 -@ Nicks-foo-bar-setup-00A0.dts
root@beaglebone:~# cp Nicks-foo-bar-setup-00A0.dtbo /lib/firmware/
root@beaglebone:~# echo Nicks-foo-bar-setup > /sys/devices/bone_capemgr.*/slots
-sh: /sys/devices/bone_capemgr.9/slots: cannot overwrite existing file

I thought it was a noclobber thing, but its not.

root@beaglebone:~# set +o noclobber
root@beaglebone:~# echo Nicks-foo-bar-setup > /sys/devices/bone_capemgr./slots
-sh: echo: write error: File exists
root@beaglebone:~# set -o noclobber
root@beaglebone:~# echo Nicks-foo-bar-setup > /sys/devices/bone_capemgr.
/slots
-sh: /sys/devices/bone_capemgr.9/slots: cannot overwrite existing file

What could be wrong?

What are you trying to do in your device tree? I’m a newbie, so take anything I say with a pinch of salt, but I seem to recall having similar problems. I was trying to enable some GPIO pins (P8_36 → P8_46) which conflicted with the HDMI framer; IIRC, I got these kinds of messages until I disabled HDMI at boot-time via uEnv.txt as per https://groups.google.com/forum/#!msg/beagleboard/1dluTWZ5AEA/Ddzm6aWCPF8J . You might have a similar conflict.

Also, have a look in the kernel message buffer (dmesg); it might spit out something useful. And take a look at ‘cat /sys/devices/bone_capemgr.*/slots’ before and after you try and enable your DTBO; see if anything changes.