hal: Disable gapless offload playback by default.

-Set the property-audio.offload.gapless.enabled to true to enable
 gapless playback by default.
-Set mixer control to the driver to decide if gapless playback needs
 to be used or not
-If gapless playback is not enabled then partial drain from HAL is
 treated as full drain.

Change-Id: Id7f4967fe528bab9097c3f609058276ec02174e1
diff --git a/hal/audio_hw.c b/hal/audio_hw.c
index ee68a8f..118239d 100644
--- a/hal/audio_hw.c
+++ b/hal/audio_hw.c
@@ -1,8 +1,8 @@
 /*
- * Copyright (c) 2013, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2013-2014, The Linux Foundation. All rights reserved.
  * Not a Contribution.
  *
- * Copyright (C) 2013 The Android Open Source Project
+ * Copyright (C) 2013-2014 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -153,6 +153,7 @@
 
 static int set_voice_volume_l(struct audio_device *adev, float volume);
 static uint32_t get_offload_buffer_size();
+static int set_gapless_mode(struct audio_device *adev);
 
 static bool is_supported_format(audio_format_t format)
 {
@@ -2138,6 +2139,9 @@
             }
         }
 
+        //Decide if we need to use gapless mode by default
+        set_gapless_mode(adev);
+
     } else if (out->flags & AUDIO_OUTPUT_FLAG_INCALL_MUSIC) {
         ret = voice_check_and_set_incall_music_usecase(adev, out);
         if (ret != 0) {
@@ -2688,6 +2692,33 @@
     return fragment_size;
 }
 
+static int set_gapless_mode(struct audio_device *adev) {
+
+
+    char value[PROPERTY_VALUE_MAX] = {0};
+    bool gapless_enabled = false;
+    const char *mixer_ctl_name = "Compress Gapless Playback";
+    struct mixer_ctl *ctl;
+
+    ALOGV("%s:", __func__);
+    property_get("audio.offload.gapless.enabled", value, NULL);
+    gapless_enabled = atoi(value) || !strncmp("true", value, 4);
+
+    ctl = mixer_get_ctl_by_name(adev->mixer, mixer_ctl_name);
+    if (!ctl) {
+        ALOGE("%s: Could not get ctl for mixer cmd - %s",
+                               __func__, mixer_ctl_name);
+        return -EINVAL;
+    }
+
+    if (mixer_ctl_set_value(ctl, 0, gapless_enabled) < 0) {
+        ALOGE("%s: Could not set gapless mode %d",
+                       __func__, gapless_enabled);
+         return -EINVAL;
+    }
+    return 0;
+
+}
 static struct hw_module_methods_t hal_module_methods = {
     .open = adev_open,
 };