firmware/layer1: mute UL/DL vocodec if it's not needed

The upper layers usually request either of the two configurations:

* (AUDIO_TX_MICROPHONE | AUDIO_RX_SPEAKER) - in this configuration
  the phone (PHY) is both the origin and the destination of the TCH
  frames.  DL frames are played via the built-in speaker; UL frames
  recorded using the built-in microphone.

* (AUDIO_TX_TRAFFIC_REQ | AUDIO_RX_TRAFFIC_IND) - in this case
  the upper layers (host side) become the origin and the destination
  of the TCH frames.  The built-in speaker and microphone are
  expected to be disabled.

However, when using the second configuration, one can still hear
DL TCH frames being played by the built-in speaker.  The built-in
microphone does not seem to be causing any issues, but still we
definitely don't want the vocoder to interfere with the host.

Change-Id: I390db1889f079dea8112794c3e039a9136b897df
Related: OS#4396
---
M src/target/firmware/include/calypso/l1_environment.h
M src/target/firmware/layer1/prim_tch.c
2 files changed, 41 insertions(+), 0 deletions(-)

diff --git a/src/target/firmware/include/calypso/l1_environment.h b/src/target/firmware/include/calypso/l1_environment.h
index d49866e..476a8a8 100644
--- a/src/target/firmware/include/calypso/l1_environment.h
+++ b/src/target/firmware/include/calypso/l1_environment.h
@@ -104,6 +104,8 @@
 #define B_PLAY_UL         (1 << 3) // Play UL
 #define B_DCO_ON          (1 << 4) // DCO ON/OFF
 #define B_AUDIO_ASYNC     (1 << 1) // WCP reserved
+#define B_MUTE_VOCODEC_DL (1 << 14) // DL voice decoder
+#define B_MUTE_VOCODEC_UL (1 << 15) // UL voice encoder
 
 // ****************************************************************
 // PARAMETER AREA (PARAM) MCU<->DSP COMMUNICATION DEFINITIONS
diff --git a/src/target/firmware/layer1/prim_tch.c b/src/target/firmware/layer1/prim_tch.c
index e3cffd1..1e3ca75 100644
--- a/src/target/firmware/layer1/prim_tch.c
+++ b/src/target/firmware/layer1/prim_tch.c
@@ -85,6 +85,18 @@
 			*tch_mode = SIG_ONLY_MODE;
 		}
 	}
+
+	/* enable/disable the voice decoder (Downlink) */
+	if (l1s.audio_mode & AUDIO_RX_SPEAKER)
+		dsp_api.ndb->d_tch_mode &= ~B_MUTE_VOCODEC_DL; /* unmute */
+	else
+		dsp_api.ndb->d_tch_mode |= B_MUTE_VOCODEC_DL; /* mute */
+
+	/* enable/disable the voice encoder (Uplink) */
+	if (l1s.audio_mode & AUDIO_TX_MICROPHONE)
+		dsp_api.ndb->d_tch_mode &= ~B_MUTE_VOCODEC_UL; /* unmute */
+	else
+		dsp_api.ndb->d_tch_mode |= B_MUTE_VOCODEC_UL; /* mute */
 }
 
 

