--- a/sys/bus/firewire/fwohci_pci.c
+++ b/sys/bus/firewire/fwohci_pci.c
@@ -342,12 +342,24 @@
 fwohci_pci_detach(device_t self)
 {
 	fwohci_softc_t *sc = device_get_softc(self);
+	int err;
 
 	crit_enter();
 	if (sc->bsr)
 		fwohci_stop(sc, self);
 
-	bus_generic_detach(self);
+	/*
+	 * Never tear our own resources down (and never force-delete the
+	 * firewire child) while a child driver is still attached and vetoed
+	 * the detach: the controller, IRQ and DMA rings must stay valid.
+	 */
+	err = bus_generic_detach(self);
+	if (err) {
+		device_printf(self, "could not detach firewire child, %d\n",
+		    err);
+		crit_exit();
+		return (err);
+	}
 	if (sc->fc.bdev) {
 		device_delete_child(self, sc->fc.bdev);
 		sc->fc.bdev = NULL;