Beagleboard:BeagleBone Debian Image Migration
What changes were made to sysfs?
3.8 kernel sysfs entry 4.x kernel sysfs entry /sys/devices/bone_capemgr.* /sys/devices/platform/bone_capemgr /sys/devices/ocp.* /sys/devices/platform/ocp/ /sys/devices/ocp.*/helper.*/AIN* /sys/bus/iio/devices/iio:device0
Help! My overlay won't load! There's just this weird cape in slot 4.
You've met cape-universal. It is meant to often make overlays unnecessary, but you can also just disable it by changing the following line in /boot/uEnv.txt:
cmdline=coherent_pool=1M quiet cape_universal=enable
cape-universal is also automatically disabled if
bone_capemgr.enable_partno occurs in the kernel cmdline (even if its argument is blank) or any overlay is already applied via capemgr before cape-universal can be loaded.
Disabling eMMC or HDMI
HDMI and eMMC are now part of the main dtb instead of being virtual CAPEs, which means that to disable these you change the 'dtb' variable in /boot/uEnv.txt instead of using capemgr.disable_partno:
See also this survey of BeagleBone DTBs.
Enabling the ADC
This requires configuring the ADC via device tree, e.g. by loading the
/lib/firmware/BB-ADC-00A0.dtbo overlay (source code) using capemgr:
echo BB-ADC >/sys/devices/platform/bone_capemgr/slots
Same story as the ADC except using uio_pruss_enable-00A0.dtbo:
echo uio_pruss_enable >/sys/devices/platform/bone_capemgr/slots