v4.19.x: BBAI + BBB = Capes

Thanks to the work of our GSOC 2020 Student Deepak Khatri!


We now have Device Tree Overlays that work on both the BBAI and BBB.

Here is the full testing list:


This will require a new version of u-boot for both BBB and BBAI, i'll
have testing images available in a day or two.

But just heads up for everyone, an upgrade to 4.19.94-ti-r47 and
4.19.94-ti-rt-r47 'might' cause a boot failure.. So only upgrade if
you have a serial console

To Upgrade u-boot on your current booting medium (eMMC or microSD) just run:

sudo /opt/scripts/tools/developers/update_bootloader.sh

Background, we are following the path of RPi's kernel, the "dtbo's"
are now built into the kernel again, so any ABI changes can be hidden.

Our previous dual repo approach, separate overlay repo and kernel
repo, made some interesting requirements of the overlay files for
v4.4.x -> v5.4.x kernel versions..

The old overlay repo will still be used, but slowly all overlays will
be moved to the kernel repo.. Thus u-boot will now search for the
*.dtbo vs just hardcoding the path..


can be written as:

1: /boot/dtbs/<uname-r>/overlays/*.dtbo
2: /lib/firmware/*.dtbo
3: / (*aka the old way..)


and test images are now up!