3 files changed, 31 insertions, 0 deletions

diff --git a/firmware/drivers/audio/eros_qn_codec.c b/firmware/drivers/audio/eros_qn_codec.c
index 21347f5fca..fdf21d2f9d 100644
--- a/firmware/drivers/audio/eros_qn_codec.c
+++ b/firmware/drivers/audio/eros_qn_codec.c
@@ -26,10 +26,14 @@
 #include "audiohw.h"
 #include "settings.h"
 #include "pcm_sw_volume.h"
+#include "gpio-x1000.h"
 
 static long int vol_l_hw = 0;
 static long int vol_r_hw = 0;
 
+/* internal: mute the headphone amp. 0 - unmuted, 1 - muted */
+void audiohw_mute_hp(int mute);
+
 void pcm5102_set_outputs(void)
 {
     audiohw_set_volume(vol_l_hw, vol_r_hw);
@@ -53,13 +57,33 @@ void audiohw_set_volume(int vol_l, int vol_r)
     if (lineout_inserted() && !headphones_inserted())
     {
         l = r = global_settings.volume_limit * 10;
+
+        /* mute the headphone amp if not plugged in */
+        audiohw_mute_hp(1);
     }
     else
     {
+        /* unmute the headphone amp when plugged in */
+        audiohw_mute_hp(0);
         l = vol_l;
         r = vol_r;
     }
 #endif
 
+    l = l <= PCM5102A_VOLUME_MIN ? PCM_MUTE_LEVEL : l;
+    r = r <= PCM5102A_VOLUME_MIN ? PCM_MUTE_LEVEL : r;
+
     pcm_set_master_volume(l, r);
 }
+
+void audiohw_mute_hp(int mute)
+{
+    if (mute == 0)
+    {
+        gpio_set_level(GPIO_MAX97220_SHDN, 1);
+    }
+    else
+    {
+        gpio_set_level(GPIO_MAX97220_SHDN, 0);
+    }
+}
diff --git a/firmware/export/eros_qn_codec.h b/firmware/export/eros_qn_codec.h
index 15c745c04b..9c900186a8 100644
--- a/firmware/export/eros_qn_codec.h
+++ b/firmware/export/eros_qn_codec.h
@@ -26,6 +26,9 @@
 #define PCM5102A_VOLUME_MIN -740
 #define PCM5102A_VOLUME_MAX 0
 
+/* a small DC offset appears to prevent play/pause clicking */
+#define PCM_DC_OFFSET_VALUE -1
+
 AUDIOHW_SETTING(VOLUME, "dB", 0, 1, PCM5102A_VOLUME_MIN/10, PCM5102A_VOLUME_MAX/10, 0)
 
 /* this just calls audiohw_set_volume() with the last (locally) known volume,
diff --git a/firmware/pcm_sw_volume.c b/firmware/pcm_sw_volume.c
index 7322269f44..3593c684af 100644
--- a/firmware/pcm_sw_volume.c
+++ b/firmware/pcm_sw_volume.c
@@ -54,7 +54,11 @@ static typeof (memcpy) *pcm_scaling_fn = NULL;
 /* Scale sample by PCM factor */
 static inline int32_t pcm_scale_sample(PCM_F_T f, int32_t s)
 {
+#if defined(PCM_DC_OFFSET_VALUE)
+    return (f * s + PCM_DC_OFFSET_VALUE) >> PCM_SW_VOLUME_FRACBITS;
+#else
     return (f * s) >> PCM_SW_VOLUME_FRACBITS;
+#endif
 }
 
 /* Both UNITY, use direct copy */