diff --git a/post_proc/volume_listener.c b/post_proc/volume_listener.c
index 62acd6f..34954bb 100644
--- a/post_proc/volume_listener.c
+++ b/post_proc/volume_listener.c
@@ -312,6 +312,13 @@
  * Effect Control Interface Implementation
  */
 
+static inline int16_t clamp16(int32_t sample)
+{
+    if ((sample>>15) ^ (sample>>31))
+        sample = 0x7FFF ^ (sample>>31);
+    return sample;
+}
+
 static int vol_effect_process(effect_handle_t self,
                               audio_buffer_t *in_buffer,
                               audio_buffer_t *out_buffer)
@@ -330,7 +337,15 @@
 
     // calculation based on channel count 2
     if (in_buffer->raw != out_buffer->raw) {
-        memcpy(out_buffer->raw, in_buffer->raw, out_buffer->frameCount * 2 * sizeof(int16_t));
+        if (context->config.outputCfg.accessMode == EFFECT_BUFFER_ACCESS_ACCUMULATE) {
+            size_t i;
+            for (i = 0; i < out_buffer->frameCount*2; i++) {
+                out_buffer->s16[i] = clamp16(out_buffer->s16[i] + in_buffer->s16[i]);
+            }
+        } else {
+            memcpy(out_buffer->raw, in_buffer->raw, out_buffer->frameCount * 2 * sizeof(int16_t));
+        }
+
     } else {
         ALOGW("%s: something wrong, didn't handle in_buffer and out_buffer same address case",
               __func__);
@@ -374,6 +389,12 @@
 
     case EFFECT_CMD_SET_CONFIG:
         ALOGV("%s :: cmd called EFFECT_CMD_SET_CONFIG", __func__);
+        if (p_cmd_data == NULL || cmd_size != sizeof(effect_config_t)
+                || p_reply_data == NULL || reply_size == NULL || *reply_size != sizeof(int)) {
+            return -EINVAL;
+        }
+        context->config = *(effect_config_t *)p_cmd_data;
+        *(int *)p_reply_data = 0;
         break;
 
     case EFFECT_CMD_GET_CONFIG:
@@ -600,7 +621,7 @@
 
 static int vol_prc_lib_create(const effect_uuid_t *uuid,
                               int32_t session_id,
-                              int32_t io_id,
+                              int32_t io_id __unused,
                               effect_handle_t *p_handle)
 {
     int itt = 0;