2 files changed, 34 insertions, 46 deletions

diff --git a/modules/usbaudio/alsa_device_profile.c b/modules/usbaudio/alsa_device_profile.c
index c7df00c..5c4edd1 100644
--- a/modules/usbaudio/alsa_device_profile.c
+++ b/modules/usbaudio/alsa_device_profile.c
@@ -275,28 +275,19 @@ static unsigned profile_enum_sample_formats(alsa_device_profile* profile, struct
 
 static unsigned profile_enum_channel_counts(alsa_device_profile* profile, unsigned min, unsigned max)
 {
-    // TODO: Don't return MONO even if the device supports it. This causes problems
-    // in AudioPolicyManager. Revisit.
-    static const unsigned std_out_channel_counts[] = {8, 4, 2/*, 1*/};
-    static const unsigned std_in_channel_counts[] = {8, 4, 2, 1};
-
-    unsigned * channel_counts =
-        profile->direction == PCM_OUT ? std_out_channel_counts : std_in_channel_counts;
-    unsigned num_channel_counts =
-        profile->direction == PCM_OUT
-            ? ARRAY_SIZE(std_out_channel_counts) : ARRAY_SIZE(std_in_channel_counts);
+    static const unsigned std_channel_counts[] = {8, 4, 2, 1};
 
     unsigned num_counts = 0;
     unsigned index;
     /* TODO write a profile_test_channel_count() */
     /* Ensure there is at least one invalid channel count to terminate the channel counts array */
-    for (index = 0; index < num_channel_counts &&
+    for (index = 0; index < ARRAY_SIZE(std_channel_counts) &&
                     num_counts < ARRAY_SIZE(profile->channel_counts) - 1;
          index++) {
         /* TODO Do we want a channel counts test? */
-        if (channel_counts[index] >= min && channel_counts[index] <= max /* &&
+        if (std_channel_counts[index] >= min && std_channel_counts[index] <= max /* &&
             profile_test_channel_count(profile, channel_counts[index])*/) {
-            profile->channel_counts[num_counts++] = channel_counts[index];
+            profile->channel_counts[num_counts++] = std_channel_counts[index];
         }
     }
 
@@ -459,6 +450,7 @@ char * profile_get_channel_count_strs(alsa_device_profile* profile)
     };
 
     const bool isOutProfile = profile->direction == PCM_OUT;
+
     const char * const * const names_array = isOutProfile ? out_chans_strs : in_chans_strs;
     const size_t names_size = isOutProfile ? ARRAY_SIZE(out_chans_strs)
             : ARRAY_SIZE(in_chans_strs);
@@ -467,12 +459,17 @@ char * profile_get_channel_count_strs(alsa_device_profile* profile)
     buffer[0] = '\0';
     const int buffer_size = ARRAY_SIZE(buffer);
     int num_entries = 0;
-    bool stereo_allowed = false;
+    /* We currently support MONO and STEREO, and always report STEREO but some (many)
+     * USB Audio Devices may only announce support for MONO (a headset mic for example), or
+     * The total number of output channels. SO, if the device itself doesn't explicitly
+     * support STEREO, append to the channel config strings we are generating.
+     */
+    bool stereo_present = false;
     unsigned index;
     unsigned channel_count;
 
     for (index = 0; (channel_count = profile->channel_counts[index]) != 0; index++) {
-        stereo_allowed = stereo_allowed || channel_count == 2;
+        stereo_present = stereo_present || channel_count == 2;
         if (channel_count < names_size && names_array[channel_count] != NULL) {
             if (num_entries++ != 0) {
                 strncat(buffer, "|", buffer_size);
@@ -480,14 +477,16 @@ char * profile_get_channel_count_strs(alsa_device_profile* profile)
             strncat(buffer, names_array[channel_count], buffer_size);
         }
     }
+
     /* emulated modes:
      * always expose stereo as we can emulate it for PCM_OUT
      */
-    if (!stereo_allowed && isOutProfile) {
+    if (!stereo_present) {
         if (num_entries++ != 0) {
             strncat(buffer, "|", buffer_size);
         }
         strncat(buffer, names_array[2], buffer_size); /* stereo */
     }
+
     return strdup(buffer);
 }
diff --git a/modules/usbaudio/audio_hw.c b/modules/usbaudio/audio_hw.c
index 664a753..0346408 100644
--- a/modules/usbaudio/audio_hw.c
+++ b/modules/usbaudio/audio_hw.c
@@ -104,9 +104,11 @@ struct stream_in {
     alsa_device_profile * profile;
     alsa_device_proxy proxy;            /* state of the stream */
 
-    // not used?
-    // struct audio_config hal_pcm_config;
-
+    unsigned hal_channel_count;         /* channel count exposed to AudioFlinger.
+                                         * This may differ from the device channel count when
+                                         * the device is not compatible with AudioFlinger
+                                         * capabilities, e.g. exposes too many channels or
+                                         * too few channels. */
     /* We may need to read more data from the device in order to data reduce to 16bit, 4chan */
     void * conversion_buffer;           /* any conversions are put into here
                                          * they could come from here too if
@@ -623,25 +625,13 @@ static int in_set_sample_rate(struct audio_stream *stream, uint32_t rate)
 static size_t in_get_buffer_size(const struct audio_stream *stream)
 {
     const struct stream_in * in = ((const struct stream_in*)stream);
-    size_t buffer_size =
-        proxy_get_period_size(&in->proxy) * audio_stream_in_frame_size(&(in->stream));
-    ALOGV("in_get_buffer_size() = %zd", buffer_size);
-
-    return buffer_size;
+    return proxy_get_period_size(&in->proxy) * audio_stream_in_frame_size(&(in->stream));
 }
 
 static uint32_t in_get_channels(const struct audio_stream *stream)
 {
-    /* TODO Here is the code we need when we support arbitrary channel counts
-     * alsa_device_proxy * proxy = ((struct stream_in*)stream)->proxy;
-     * unsigned channel_count = proxy_get_channel_count(proxy);
-     * uint32_t channel_mask = audio_channel_in_mask_from_count(channel_count);
-     * ALOGV("in_get_channels() = 0x%X count:%d", channel_mask, channel_count);
-     * return channel_mask;
-     */
-    /* TODO When AudioPolicyManager & AudioFlinger supports arbitrary channels
-     rewrite this to return the ACTUAL channel format */
-    return AUDIO_CHANNEL_IN_STEREO;
+    const struct stream_in *in = (const struct stream_in*)stream;
+    return audio_channel_in_mask_from_count(in->hal_channel_count);
 }
 
 static audio_format_t in_get_format(const struct audio_stream *stream)
@@ -808,7 +798,7 @@ static ssize_t in_read(struct audio_stream_in *stream, void* buffer, size_t byte
      */
     num_read_buff_bytes = bytes;
     int num_device_channels = proxy_get_channel_count(&in->proxy);
-    int num_req_channels = 2; /* always, for now */
+    int num_req_channels = in->hal_channel_count;
 
     if (num_device_channels != num_req_channels) {
         num_read_buff_bytes = (num_device_channels * num_read_buff_bytes) / num_req_channels;
@@ -960,19 +950,18 @@ static int adev_open_input_stream(struct audio_hw_device *dev,
         ret = -EINVAL;
     }
 
-    if (config->channel_mask == AUDIO_CHANNEL_NONE) {
-        /* just return AUDIO_CHANNEL_IN_STEREO until the framework supports other input
-         * formats */
-        config->channel_mask = AUDIO_CHANNEL_IN_STEREO;
-
-    } else if (config->channel_mask != AUDIO_CHANNEL_IN_STEREO) {
-        /* allow only stereo capture for now */
-        config->channel_mask = AUDIO_CHANNEL_IN_STEREO;
-        ret = -EINVAL;
+    /* Channels */
+    unsigned proposed_channel_count = profile_get_default_channel_count(in->profile);
+    if (k_force_channels) {
+        proposed_channel_count = k_force_channels;
+    } else if (config->channel_mask != AUDIO_CHANNEL_NONE) {
+        proposed_channel_count = audio_channel_count_from_in_mask(config->channel_mask);
     }
-    // proxy_config.channels = 0;  /* don't change */
-    proxy_config.channels = profile_get_default_channel_count(in->profile);
 
+    /* we can expose any channel count mask, and emulate internally. */
+    config->channel_mask = audio_channel_in_mask_from_count(proposed_channel_count);
+    in->hal_channel_count = proposed_channel_count;
+    proxy_config.channels = profile_get_default_channel_count(in->profile);
     proxy_prepare(&in->proxy, in->profile, &proxy_config);
 
     in->standby = true;