ALSA: hda - Clear the dropped paths properly

When a DAC is reassigned from surrounds to front or ADCs are reduced
due to incomplete imux, we clear the path indices but the path
instances remain as is.  Since the paths might be still referred
through the whole path list parsing (e.g. is_active_nid()), we should
clear these path instances as well.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_generic.c

@@ -331,6 +331,15 @@ snd_hda_add_new_path(struct hda_codec *codec, hda_nid_t from_nid,
 }
 EXPORT_SYMBOL_HDA(snd_hda_add_new_path);
 
+/* clear the given path as invalid so that it won't be picked up later */
+static void invalidate_nid_path(struct hda_codec *codec, int idx)
+{
+	struct nid_path *path = snd_hda_get_path_from_idx(codec, idx);
+	if (!path)
+		return;
+	memset(path, 0, sizeof(*path));
+}
+
 /* look for an empty DAC slot */
 static hda_nid_t look_for_dac(struct hda_codec *codec, hda_nid_t pin,
 			      bool is_digital)
@@ -891,10 +900,12 @@ static int try_assign_dacs(struct hda_codec *codec, int num_outs,
 
 		dacs[i] = look_for_dac(codec, pin, false);
 		if (!dacs[i] && !i) {
+			/* try to steal the DAC of surrounds for the front */
 			for (j = 1; j < num_outs; j++) {
 				if (is_reachable_path(codec, dacs[j], pin)) {
 					dacs[0] = dacs[j];
 					dacs[j] = 0;
+					invalidate_nid_path(codec, path_idx[j]);
 					path_idx[j] = 0;
 					break;
 				}
@@ -2046,10 +2057,13 @@ static int check_dyn_adc_switch(struct hda_codec *codec)
 				continue;
 			if (n != nums) {
 				spec->adc_nids[nums] = spec->adc_nids[n];
-				for (i = 0; i < imux->num_items; i++)
+				for (i = 0; i < imux->num_items; i++) {
+					invalidate_nid_path(codec,
+						spec->input_paths[i][nums]);
 					spec->input_paths[i][nums] =
 						spec->input_paths[i][n];
 				}
+			}
 			nums++;
 		}
 		spec->num_adc_nids = nums;