CM256SM Wifi is painful

I got one of those dreaded CM256SM wifi models. And it just has been a pain. The images from radxa work (mostly) with the wifi but as soon as you update/upgrade your OS the wifi goes away again. The official Armbian (Ubuntu) and Manjaro distributions do not work with that wifi out of the box which is very concerning because those issues have been known for quite some time and the fixes have not been able to bubble up since, which does not give me enough confidence in future support from Radxa. I personally don’t want to deal with bespoke kernel patches and wifi firmware every time I update my OS. Including the mandatory Serial TTY login and fixing procedure … because no connection anymore. I think I am going to send the boards back. If anyone has a a board without this awful wifi chip I might give it another try.

You just have to place the brcm firmware in firmware directory and there is no need for any other change in the kernel.

Zero had multiple chips used and must upstream distro only added the firmware of the board which was set to them as development unit.

Which firmware files to be exact? And what driver package does the chip use exactly? I copied some firmware and got rid of the bluetooth errors in dmesg but still had no wifi. Strange thing was also that I could not see anything wifi related in the log nor there was an lspci or lsusb device but I admit that was was unsure what to look for.

And after I set up the system with wifi working once (armbian/ubuntu) with all updates and software that I need etc. and wifi was gone again after the next reboot with no errors to act on I lost confidence.

sudo dmesg | grep brcm

This just printed Bluetooth related errors of the chip and if I fix them by pointing to the firmware the wifi still does not come on.

Ok so I figured out some more pieces the wifi Bluetooth combo is connected to the SDIO bus and I get: error -84 whilst initializing SDIO card on boot
and in the pre kernel boot sequence I get: Card did not respond to voltage select! : -110

How about try to set the SDIO frequency lower?

I was thinking about that. What is the procedure and recommended values to try?