+static int q6usb_update_offload_route(struct snd_soc_component *component, int card,
+				      int pcm, int direction, long *route)
+{
+	struct q6usb_port_data *data = dev_get_drvdata(component->dev);
+	struct snd_soc_usb_device *sdev;
+	int ret = 0;
+	int cidx = -1;
+	int pidx = -1;
+
+	mutex_lock(&data->mutex);
+
+	if (list_empty(&data->devices) ||
+	    direction == SNDRV_PCM_STREAM_CAPTURE) {
+		ret = -ENODEV;
+		goto out;
+	}

well the code above seems to invalidate what I understood earlier, in
that an error code is returned instead of a set of -1 values...

+
+	sdev = list_last_entry(&data->devices, struct snd_soc_usb_device, list);
+
+	/*
+	 * Will always look for last PCM device discovered/probed as the
+	 * active offload index.
+	 */
+	if (card == sdev->card_idx &&
+	    pcm == sdev->ppcm_idx[sdev->num_playback - 1]) {
+		cidx = component->card->snd_card->number;
+		pidx = q6usb_get_pcm_id(component);
+	}
+
+	if (cidx < 0 || pidx < 0) {
+		cidx = -1;
+		pidx = -1;
+	}
+
+out:
+	route[0] = cidx;
+	route[1] = pidx;
+
+	mutex_unlock(&data->mutex);
+
+	return ret;
+}
+