pipewire >= 0.3.64 fills kernel log with " ASoC: no backend DAIs enabled for ... Port" errors
The last couple of months the kernel logs on many different Bay Trail models (using ASoC Intel SSP audio) have been filling up with messages like these:
[ 43.244549] Baytrail Audio Port: ASoC: no backend DAIs enabled for Baytrail Audio Port [ 43.244744] Baytrail Audio Port: ASoC: error at dpcm_fe_dai_prepare on Baytrail Audio Port: -22
in total 48 lines (24 repeats of the above) are logged when pipewire starts in the gdm session + another 48 when the user logs in.
I've managed to pin this down on being caused by changes in pipewire first starting in pipewire-0.3.64, installing pipewire-0.3.63 from koji (on a not yet updated Fedora 36) install makes the problem go away and installing pipewire-0.3.64-1 from koji causes the log messages to appear.
I have made the kernel generate a backtrace when it prints the warning and these warnings are being triggered by the SNDRV_PCM_IOCTL_PREPARE ioctl.
I believe that these warnings are being caused by the SNDRV_PCM_IOCTL_PREPARE ioctl now being called by pipewire before applying the mixer settings from the UCM profile, which causes the backend and frontend DAI to not be linked to each other yet when the ioctl is made.