Linux/Airpods Pro Headset mode not working of Fedora38 - Don't forget about Bluetooth adapter firmware! Also fix helvum breakage.
After getting a pair of Airpods Pro and connecting them to Fedora 38 computer I found that I could use them as "headphones" but not as a "handset". Pairing was easy using the utility bluetoothctl - put the airpods in pairing mode, run bluetoothctl and then issue the "pair" command giving the proper hex string e.g. as in https://meroupatate.github.io/posts/airpods/ . Once this is done, the "headphone" device as well as the "handsfree" device shows up in the Sound section of "Settings" and can be selected but the this doesn't result in the airpods being able to do anything useful in handsfree mode. In theory, the problem could be in the Linux Software Sound stack (some combination of Pipewire, Pulse Audio, Alsa), or with the various codecs installed on the system. Most of the resources on the internet focus here. Since I'm on Fedora 38 Pipewire is well established. One other wrinkle about this is that somewhere in