BeagleBone Black Device Tree Overlays Not Applying

0
votes

I am trying to create a device tree overlay for a BeagleBone Black per these instructions: http://derekmolloy.ie/gpios-on-the-beaglebone-black-using-device-tree-overlays/. I followed the directions exactly as shown and was not told of any errors, except after I try to apply the overlay (with echo DM-GPIO-Test > $SLOTS), it doesn't seem to actually work. Using cat $SLOTS shows everything how it is supposed to be:

root@beaglebone:/lib/firmware# cat $SLOTS
 0: 54:PF--- 
 1: 55:PF--- 
 2: 56:PF--- 
 3: 57:PF--- 
 4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
 5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
 6: ff:P-O-L Override Board Name,00A0,Override Manuf,DM-GPIO-Test

However, if I cat $PINS none of the values have changed from the original, and the dmesg command does not return any of the expected output (shown on the linked site). I have also looked at several other sites about overlays, with more or less the same instructions, which are also unsuccessful. I've tried other overlays as well, and tested on multiple BeagleBone Black boards, with no success.

I am using the 3.8.13 kernel with Angstrom, essentially unmodified except for what's in that tutorial.

1
gpiobeagleboneblackdevice-tree
First of all, just a tip: when setting the SLOTS environment variable, use a "*" in place of the number. export SLOTS=/sys/devices/bone_capemgr.*/slots Just a nice fail-safe I guess. Now for the real problem, have you tried checking the pingroups to see if the overlay actually worked? cat /sys/kernel/debug/pinctrl/44e10800.pinmux/pingroups – woojoo666
Also, I highly recommend this tutorial: learn.adafruit.com/… – woojoo666
Yup, I know about the $SLOTS thing. I have tried that tutorial as well. I'm having this problem with other DTOs as well, even the default ones found in /lib/firmware/ that came with the BeagleBone. – siamesedrummer
did you try checking the pingroups? were any new pins enabled? – woojoo666
like "cat $PINS"? No, all were the same as previously. – siamesedrummer

1 Answers

-1
votes

you have to run the command as root.