ErosQ Native: Add DC Offset to PCM data

A small negative offset seems to silence all
play/pause clicking on the PCM5102A.

Also adding PCM soft muting, and muting the headphone amp
when the headphones are detected as removed. This has been
tested to not cause any unintended side effects on the
line out.

Also confirmed the numerical dB values are (approx.) correct.

Change-Id: I689d68887c86add9cc5e0ccb0c7de01aaa69b4d9

1 files changed, 24 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);
+    }
+}