audio hal: report index channel masks for USB

Report only index channel masks for USB output profiles
supporting more than two channels.

Bug: 120947396
Test: play multichannel audio over USB
Change-Id: I10f6d4751a5a17674d24fb0d074f1dd6a71a06e1
(cherry picked from commit d01f3972959d9e2c22d35d15d0f55c6d9e088694)
diff --git a/hal/audio_hw.c b/hal/audio_hw.c
index 07f5cee..9f29706 100644
--- a/hal/audio_hw.c
+++ b/hal/audio_hw.c
@@ -1845,14 +1845,31 @@
     channel_count = DEFAULT_CHANNEL_COUNT;
 
     if (is_playback) {
-        // For playback we never report mono because the framework always outputs stereo
-        // audio_channel_out_mask_from_count() does return positional masks for channel counts
-        // above 2 but we want indexed masks here.
-        supported_channel_masks[num_masks++] = audio_channel_out_mask_from_count(channel_count);
+        // start from 2 channels as framework currently doesn't support mono.
+        if (channels >= FCC_2) {
+            supported_channel_masks[num_masks++] = audio_channel_out_mask_from_count(FCC_2);
+        }
+        for (channel_count = FCC_2;
+                channel_count <= channels && num_masks < max_masks;
+                ++channel_count) {
+            supported_channel_masks[num_masks++] =
+                    audio_channel_mask_for_index_assignment_from_count(channel_count);
+        }
     } else {
         // audio_channel_in_mask_from_count() does the right conversion to either positional or
         // indexed mask
-        supported_channel_masks[num_masks++] = audio_channel_in_mask_from_count(channel_count);
+        for ( ; channel_count <= channels && num_masks < max_masks; channel_count++) {
+            audio_channel_mask_t mask = AUDIO_CHANNEL_NONE;
+            if (channel_count <= FCC_2) {
+                mask = audio_channel_in_mask_from_count(channel_count);
+                supported_channel_masks[num_masks++] = mask;
+            }
+            const audio_channel_mask_t index_mask =
+                    audio_channel_mask_for_index_assignment_from_count(channel_count);
+            if (mask != index_mask && num_masks < max_masks) { // ensure index mask added.
+                supported_channel_masks[num_masks++] = index_mask;
+            }
+        }
     }
 
     for (channel_count = channels; ((channel_count >= DEFAULT_CHANNEL_COUNT) &&