[solved] GPIO on UP^2 with more recent kernels/ubuntu is a non-starter
This isn't communicated clearly enough in the documentation and it takes reading through a lot of posts and kernel patches to get to the bottom of things. If I'd seen a post like this I would have saved time and money, so I'm making this post to give others considering this purchase more information so that they can make a better-informed choice than I did.
The documentation is clear about what is officially supported by the vendor, but the forum posts give the impression that you can install patched kernels and get things working. That is obviously not supported by the vendor, but it is also misleading: for the UP^2 there is literally no code in those patches and thus literally no support.
I purchased the up squared with the impression that the kernel was actively supported and developed in the open, and that the various devices in the shop are actively supported. That appears to be true with a cursory glance, but having now spent a good chunk of time over the past few days trying to get a system bootstrapped, I'm regretting my purchase.
The current state of the world based on what I've been able to extract from these forums and the available source code is:
- The officially supported kernel code has had no changes since August 2017 and is based on kernel 4.9
- There are some patches floating around for Arch linux that compile against a newer kernel, but they only work with the "UP" board, not the "UP^2" board
- There's talk in these forums of work being done to upstream the required changes to the linux kernel, but there's no activity in the github repo and no links to that work
- Similarly, there's talk of releasing a kernel for more recent Ubuntu, but that is blocked on the above. It has been many months since those posts were made in the forums with no visible progress.
- Since the hardware is not open, there is no documentation available for the community to be able to add support for themselves
My advice to future buyers is: if you're not going to be content sticking with a somewhat stale and opaque flavor of linux, think carefully about buying in to the "UP" ecosystem.
I know this post has a critical tone, so I also want to clarify that I love the idea of this project, and I think the selection of add-ons in the shop are great (a low power SBC + UPS was just the hardware platform I was looking for!). What I feel is lacking at the moment is transparency around what is happening to keep that ecosystem up to date.