A snd_hda driver is split into multiple child devices but there's only one PCI device with one interrupt handler. The child devices are just the way the driver organizes itself internally but they aren't real devices if you ask me. They all share the same lock for example. The bus_*_intr interface isn't used.

Use DRIVER_MODULE_ORDERED

It's just to respect AR and CC. I discovered this on a system where everything is built with ports llvm (no base system compiler installed).

In D50393#1152501, @christos wrote:

I haven't tested this for a few days, but I remember that even without the Makefile change, things worked as expected. Is this not the case?

Yes, when unloading a kernel module the drivers defined with DRIVER_MODULE appear to be deleted in reverse order.

Drain callout and taskqueue before shutting down child devices

In D46502#1066069, @jrtc27 wrote:

I've submitted a patch for exp-run in https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=281674.

Well that doesn't even do MACHINE, which is important, otherwise you'll end up with MACHINE not matching MACHINE_ARCH, which breaks things. You can't in general just set one; that's a custom feature of the src tree's Makefile.