Some fixes. Added conf for trident

src/cards/Makefile.am

@@ -1,5 +1,5 @@
 alsadir = $(datadir)/alsa/cards
-cfg_files = SI_7018.conf EMU10K1.conf
+cfg_files = SI_7018.conf EMU10K1.conf TRID4DWAVENX.conf
 
 EXTRA_DIST = $(cfg_files)
 alsa_DATA = $(cfg_files)

src/cards/TRID4DWAVENX.conf

@@ -0,0 +1,40 @@
+pcm.iec958_0 {
+	@args [ CARD DEV AES0 AES1 AES2 AES3 ]
+	@args.CARD {
+		type integer
+	}
+	@args.DEV {
+		type integer
+	}
+	@args.AES0 {
+		type integer
+	}
+	@args.AES1 {
+		type integer
+	}
+	@args.AES2 {
+		type integer
+	}
+	@args.AES3 {
+		type integer
+	}
+	type hooks
+	slave.pcm {
+		type hw
+		card $(CARD)
+		device 2
+	}
+	hooks.0 {
+		type ctl_elems
+		hook_args [
+			{
+				interface PCM
+				name "IEC958 Playback PCM Stream"
+				value [ $(AES0) $(AES1) $(AES2) $(AES3) ]
+				device 2
+				lock true
+				preserve true
+			}
+		]
+	}
+}

src/conf.c

@@ -1864,6 +1864,15 @@ static int _snd_config_expand(snd_config_t *src,
 
 void snd_config_substitute(snd_config_t *dst, snd_config_t *src)
 {
+	if (src->type == SND_CONFIG_TYPE_COMPOUND) {
+		snd_config_iterator_t i, next;
+		snd_config_for_each(i, next, src) {
+			snd_config_t *n = snd_config_iterator_entry(i);
+			n->father = dst;
+		}
+		src->u.compound.fields.next->prev = &dst->u.compound.fields;
+		src->u.compound.fields.prev->next = &dst->u.compound.fields;
+	}
 	free(dst->id);
 	dst->id  = src->id;
 	dst->type = src->type;

src/control/setup.c

@@ -460,6 +460,7 @@ static int add_elem(snd_sctl_t *h, snd_config_t *conf,
 				free(tmp);
 				goto _err;
 			}
+			iface = err;
 			free(tmp);
 			continue;
 		}