Wowbagger

Best source of documentation IMHO is from the armbian source.  These references should provide the needed description to make a usable device tree. They are mirrored here:
SPI Controller Generic Binding This binding is for display panels using an Ilitek ILI9341 controller in SPImode.
Device tree bindings for TI's ADS7843, ADS7845, ADS7846, ADS7873, TSC2046SPI driven touch screen controllers.
The other tidbit of info is the structure of a gpio cell property. AFAIK the numeric values for <&pio 0 2 1> refers to pin group 0 = A, pin offset 2 (A2), and pull-up flag.
 
Also, it is required to configure and activate the device trees. Configuration, like param_spidev_spi_bus=0, is still a mystery to me. armbian-config doesn't automatically add these items to /boot/armbianEnv.txt so this can be a major source of frustration.
 
My example /boot/armbianEnv.txt:
verbosity=7 dtdebug=7 bootlogo=false console=serial disp_mode=1920x1080p60 overlay_prefix=sun50i-h5 overlays=spi-spidev param_spidev_spi_bus=0 user_overlays=sun50i-h5-ili9341 usbstoragequirks=0x2537:0x1066:u,0x2537:0x1068:u rootdev=UUID=8d9edae5-2ab9-4c42-933e-ee4235da815f rootfstype=ext4 I created sun50i-h5-ili9341 using the referenced documentation as a guide.

Working on an embedded SBC home automation application with a very small form factor. Size and reliability is at a premium. Just want to have a smart device at the door that will help notify and find me when someone presses the doorbell button, or detects motion at the entrance or curbside mailbox. Two way audio and outbound alerts are progressing nicely but complexity increases significantly when integrating video into the solution.
 
For example, two widely used video trans-coding applications, ffmpeg and gstreamer, may or may not have hardware assisted image signal processing on the SBC. Is any form of image signal processing within scope when a board is supported by Armbian? How is hardware assisted image signal processing qualified within Armbian? I'm trying to set my expectations.
 
BTW. I had the opportunity to follow the Armbian cross-compile recipe and build environment last weekend. I was blown away with how seamless and truly useful the Armbian suite made the entire effort. Thank you to the entire team.