[Qemu-devel] [PATCH 02/11] audio: don't apply volume effect if backend has VOICE_VOLUME_CAP

["Marc-André Lureau" <marcandre.lureau@gmail.com>]

If the audio backend is capable of volume control, don't apply
software volume (mixeng_volume ()), but instead, rely on backend
volume control. This will allow guest to have full range volume
control.
---
 audio/audio.c          |    9 +++++++--
 audio/audio_int.h      |    5 +++++
 audio/audio_template.h |    2 ++
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/audio/audio.c b/audio/audio.c
index d76c342..bd9237e 100644
--- a/audio/audio.c
+++ b/audio/audio.c
@@ -957,7 +957,9 @@ int audio_pcm_sw_read (SWVoiceIn *sw, void *buf, int size)
         total += isamp;
     }
 
-    mixeng_volume (sw->buf, ret, &sw->vol);
+    if (!(hw->ctl_caps & VOICE_VOLUME_CAP)) {
+        mixeng_volume (sw->buf, ret, &sw->vol);
+    }
 
     sw->clip (buf, sw->buf, ret);
     sw->total_hw_samples_acquired += total;
@@ -1041,7 +1043,10 @@ int audio_pcm_sw_write (SWVoiceOut *sw, void *buf, int size)
     swlim = audio_MIN (swlim, samples);
     if (swlim) {
         sw->conv (sw->buf, buf, swlim);
-        mixeng_volume (sw->buf, swlim, &sw->vol);
+
+        if (!(sw->hw->ctl_caps & VOICE_VOLUME_CAP)) {
+            mixeng_volume (sw->buf, swlim, &sw->vol);
+        }
     }
 
     while (swlim) {
diff --git a/audio/audio_int.h b/audio/audio_int.h
index 117f95e..b9b0676 100644
--- a/audio/audio_int.h
+++ b/audio/audio_int.h
@@ -82,6 +82,7 @@ typedef struct HWVoiceOut {
     int samples;
     QLIST_HEAD (sw_out_listhead, SWVoiceOut) sw_head;
     QLIST_HEAD (sw_cap_listhead, SWVoiceCap) cap_head;
+    int ctl_caps;
     struct audio_pcm_ops *pcm_ops;
     QLIST_ENTRY (HWVoiceOut) entries;
 } HWVoiceOut;
@@ -101,6 +102,7 @@ typedef struct HWVoiceIn {
 
     int samples;
     QLIST_HEAD (sw_in_listhead, SWVoiceIn) sw_head;
+    int ctl_caps;
     struct audio_pcm_ops *pcm_ops;
     QLIST_ENTRY (HWVoiceIn) entries;
 } HWVoiceIn;
@@ -150,6 +152,7 @@ struct audio_driver {
     int max_voices_in;
     int voice_size_out;
     int voice_size_in;
+    int ctl_caps;
 };
 
 struct audio_pcm_ops {
@@ -233,6 +236,8 @@ void audio_run (const char *msg);
 #define VOICE_DISABLE 2
 #define VOICE_VOLUME 3
 
+#define VOICE_VOLUME_CAP (1 << VOICE_VOLUME)
+
 static inline int audio_ring_dist (int dst, int src, int len)
 {
     return (dst >= src) ? (dst - src) : (len - src + dst);
diff --git a/audio/audio_template.h b/audio/audio_template.h
index e62a713..519432a 100644
--- a/audio/audio_template.h
+++ b/audio/audio_template.h
@@ -263,6 +263,8 @@ static HW *glue (audio_pcm_hw_add_new_, TYPE) (struct audsettings *as)
     }
 
     hw->pcm_ops = drv->pcm_ops;
+    hw->ctl_caps = drv->ctl_caps;
+
     QLIST_INIT (&hw->sw_head);
 #ifdef DAC
     QLIST_INIT (&hw->cap_head);
-- 
1.7.7.6