Hi!
I am using HiFiBerry Digi+ for optical toslink input. At first it works OK, when the input is connected, I get the sound, and when the input is not connected, I cannot read any data and get "I2S SYNC error!" in dmesg. This is as expected.
What is not expected however is that after several days of a disconnected signal it does not recover, i.e. even when the signal is reconnected I can still read no data until I reboot.
It is worth mentioning that I use a Fedora kernel, not armbian. I think the problem might be in the kernel, but I can't figure out what it is.