Loading snd_hda(4) on powerpc64 as a module causes a NULL dereference in hdaa_attach() on powerpc64. It works fine when built into the kernel, and loads correctly as a module on powerpc(32) and powerpcspe.
The backtrace points to hdac_if.h:43, which is in HDAC_CODEC_COMMAND().
It appears the KOBJLOOKUP() fails, returning a NULL pointer. There may be a bug in the module loading on powerpc64.
A workaround was committed in r348250, compiling snd_hda(4) into GENERIC64, just as is done in amd64's GENERIC.