audio_route: check no used before mixer reset

The audio_route_update_path is used for enabling/disabling audio paths
by HAL, and all mixer controls will be reset in a path when the path is
disabled by HAL. However, some mixer controls are used by multiple audio
paths then such disabling operation might cause the failure on other
paths. To prevent from resetting the used controls, add the active count
for checking if the control can be reset before actually setting the
mixer control.

Bug: 117310706
Bug: 118646089
Test: VoIP (FB Messenger/Hangouts/Skype)
Change-Id: I9c25e9a9651fe27052b52155801ab54ec19156ee
Signed-off-by: HW Lee <[email protected]>

audio_route/audio_route.c

@@ -45,6 +45,7 @@ struct mixer_state {
     union ctl_values old_value;
     union ctl_values new_value;
     union ctl_values reset_value;
+    unsigned int active_count;
 };
 
 struct mixer_setting {
@@ -599,6 +600,7 @@ static int alloc_mixer_state(struct audio_route *ar)
 
         ar->mixer_state[i].ctl = ctl;
         ar->mixer_state[i].num_values = num_values;
+        ar->mixer_state[i].active_count = 0;
 
         /* Skip unsupported types that are not supported yet in XML */
         type = mixer_ctl_get_type(ctl);
@@ -797,7 +799,6 @@ static int audio_route_update_path(struct audio_route *ar, const char *name, boo
         return -1;
     }
 
-
     for (size_t i = 0; i < path->length; ++i) {
         unsigned int ctl_index;
         enum mixer_ctl_type type;
@@ -811,23 +812,53 @@ static int audio_route_update_path(struct audio_route *ar, const char *name, boo
             continue;
         }
 
+        if (reverse && ms->active_count > 0) {
+            ms->active_count--;
+        } else if (!reverse) {
+            ms->active_count++;
+        }
+
        size_t value_sz = sizeof_ctl_type(type);
         /* if any value has changed, update the mixer */
         for (j = 0; j < ms->num_values; j++) {
             if (type == MIXER_CTL_TYPE_BYTE) {
                 if (ms->old_value.bytes[j] != ms->new_value.bytes[j]) {
+                    if (reverse && ms->active_count > 0) {
+                        ALOGD("%s: skip to reset mixer control '%s' in path '%s' "
+                            "because it is still needed by other paths", __func__,
+                            mixer_ctl_get_name(ms->ctl), name);
+                        memcpy(ms->new_value.bytes, ms->old_value.bytes,
+                            ms->num_values * value_sz);
+                        break;
+                    }
                     mixer_ctl_set_array(ms->ctl, ms->new_value.bytes, ms->num_values);
                     memcpy(ms->old_value.bytes, ms->new_value.bytes, ms->num_values * value_sz);
                     break;
                 }
             } else if (type == MIXER_CTL_TYPE_ENUM) {
                 if (ms->old_value.enumerated[j] != ms->new_value.enumerated[j]) {
+                    if (reverse && ms->active_count > 0) {
+                        ALOGD("%s: skip to reset mixer control '%s' in path '%s' "
+                            "because it is still needed by other paths", __func__,
+                            mixer_ctl_get_name(ms->ctl), name);
+                        memcpy(ms->new_value.enumerated, ms->old_value.enumerated,
+                            ms->num_values * value_sz);
+                        break;
+                    }
                     mixer_ctl_set_value(ms->ctl, 0, ms->new_value.enumerated[0]);
                     memcpy(ms->old_value.enumerated, ms->new_value.enumerated,
                             ms->num_values * value_sz);
                     break;
                 }
             } else if (ms->old_value.integer[j] != ms->new_value.integer[j]) {
+                if (reverse && ms->active_count > 0) {
+                    ALOGD("%s: skip to reset mixer control '%s' in path '%s' "
+                        "because it is still needed by other paths", __func__,
+                        mixer_ctl_get_name(ms->ctl), name);
+                    memcpy(ms->new_value.integer, ms->old_value.integer,
+                        ms->num_values * value_sz);
+                    break;
+                }
                 mixer_ctl_set_array(ms->ctl, ms->new_value.integer, ms->num_values);
                 memcpy(ms->old_value.integer, ms->new_value.integer, ms->num_values * value_sz);
                 break;