GPIO not working on the BeagleBoneAI64 with firmware versions after April 2023

[kevinacahalan]

GPIO does not work on the BeagleBoneAI64 with firmware versions after April 2023. It neither works from Linux, or from an R5 core.

With some no not so thorough testing, I have found that with the images before bbai64-emmc-flasher-debian-11.6-minimal-arm64-2023-04-06-4gb.img.xz inclusive, I am still able to control GPIO. With the images after bbai64-emmc-flasher-debian-11.6-minimal-arm64-2023-04-06-4gb.img.xz I can not control GPIO.

• Here's a GPIO toggle program for testing GPIO from an R5 https://github.com/FredEckert/bbai64_cortex-r5_example/tree/r5_toggle.
• GPIO test stuff for Linux gpiod.zip. Make sure to run the C program, some of the scripts did not work for whatever reason.

I initially hit this bug after I updated my BBAI64 and ran the eMMC firmware update scripts.

Take a look at the #beaglebone-ai-64 channel in Discord to see discussion.

[jadonk]

@RobertCNelson is this a BeagleBoard-DeviceTrees regression? @lorforlinux - Can you check this?

[RobertCNelson]

@jadonk yeap it's a regression, it's a little fun as it seems to have been caused by the r5 firwmare/u-boot combination..