ALSA: hda - Fix pending unsol events at shutdown

This is an alternative fix attemp for the issue reported in the commit
caa8422d ("ALSA: hda: Flush interrupts on disabling") that was
reverted later due to regressions.  Instead of tweaking the hardware
disablement order and the enforced irq flushing, do calling
cancel_work_sync() of the unsol work early enough, and explicitly
ignore the unsol events during the shutdown by checking the
bus->shutdown flag.

Fixes: caa8422d ("ALSA: hda: Flush interrupts on disabling")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://lore.kernel.org/r/s5h1ruxt9cz.wl-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_bind.c

@@ -43,6 +43,10 @@ static void hda_codec_unsol_event(struct hdac_device *dev, unsigned int ev)
 {
 	struct hda_codec *codec = container_of(dev, struct hda_codec, core);
 
+	/* ignore unsol events during shutdown */
+	if (codec->bus->shutdown)
+		return;
+
 	if (codec->patch_ops.unsol_event)
 		codec->patch_ops.unsol_event(codec, ev);
 }

sound/pci/hda/hda_intel.c

@@ -1389,8 +1389,11 @@ static int azx_free(struct azx *chip)
 static int azx_dev_disconnect(struct snd_device *device)
 {
 	struct azx *chip = device->device_data;
+	struct hdac_bus *bus = azx_bus(chip);
 
 	chip->bus.shutdown = 1;
+	cancel_work_sync(&bus->unsol_work);
+
 	return 0;
 }