Added zero crossing check before changing volume to avoid noise during volume changes. Removed extra volume sets. Added delay for vref to settle per app notes to reduce start up clicks.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@12001 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 18 insertions, 10 deletions

diff --git a/firmware/drivers/wm8975.c b/firmware/drivers/wm8975.c
index 12aa46821a..89e0b155da 100644
--- a/firmware/drivers/wm8975.c
+++ b/firmware/drivers/wm8975.c
@@ -41,6 +41,11 @@
 #include "wm8975.h"
 #include "i2s.h"
 
+/* use zero crossing to reduce clicks during volume changes */
+#define VOLUME_ZC_WAIT (1<<7)
+
+
+
 /* convert tenth of dB volume (-730..60) to master volume register value */
 int tenthdb2master(int db)
 {
@@ -96,6 +101,9 @@ void audiohw_enable_output(bool enable)
     
          /* 2. Enable Vmid and VREF. */
         wmcodec_write(PWRMGMT1, 0xc0);    /*Pwr Mgmt(1)*/
+
+        /* From app notes: allow Vref to stabilize to reduce clicks */
+        sleep(HZ/4);
     
          /* 3. Enable DACs as required. */
         wmcodec_write(PWRMGMT2, 0x180);    /*Pwr Mgmt(2)*/
@@ -111,10 +119,8 @@ void audiohw_enable_output(bool enable)
         audiohw_set_sample_rate(WM8975_44100HZ);
     
         /* set the volume to -6dB */
-        wmcodec_write(LOUT1VOL, IPOD_PCM_LEVEL);
-        wmcodec_write(ROUT1VOL,0x100 | IPOD_PCM_LEVEL);
-        wmcodec_write(LOUT1VOL, IPOD_PCM_LEVEL);
-        wmcodec_write(ROUT1VOL,0x100 | IPOD_PCM_LEVEL);
+        wmcodec_write(LOUT1VOL, VOLUME_ZC_WAIT | IPOD_PCM_LEVEL);
+        wmcodec_write(ROUT1VOL, VOLUME_ZC_WAIT | 0x100 | IPOD_PCM_LEVEL);
 
         wmcodec_write(LOUTMIX1, 0x150);    /* Left out Mix(def) */
         wmcodec_write(LOUTMIX2, 0x50);
@@ -131,6 +137,8 @@ void audiohw_enable_output(bool enable)
     }
 }
 
+
+
 int audiohw_set_master_vol(int vol_l, int vol_r)
 {
     /* +6 to -73dB 1dB steps (plus mute == 80levels) 7bits */
@@ -140,8 +148,8 @@ int audiohw_set_master_vol(int vol_l, int vol_r)
     /* 0101111 == mute (0x2f) */
 
     /* OUT1 */
-    wmcodec_write(LOUT1VOL, vol_l);
-    wmcodec_write(ROUT1VOL, 0x100 | vol_r);
+    wmcodec_write(LOUT1VOL, VOLUME_ZC_WAIT | vol_l);
+    wmcodec_write(ROUT1VOL, VOLUME_ZC_WAIT | 0x100 | vol_r);
 
     return 0;
 }
@@ -149,8 +157,8 @@ int audiohw_set_master_vol(int vol_l, int vol_r)
 int audiohw_set_lineout_vol(int vol_l, int vol_r)
 {
     /* OUT2 */
-    wmcodec_write(LOUT2VOL, vol_l);
-    wmcodec_write(ROUT2VOL, 0x100 | vol_r);
+    wmcodec_write(LOUT2VOL, VOLUME_ZC_WAIT | vol_l);
+    wmcodec_write(ROUT2VOL, VOLUME_ZC_WAIT | 0x100 | vol_r);
 
     return 0;
 }
@@ -267,7 +275,7 @@ void audiohw_enable_recording(bool source_mic)
 
     if (source_mic) {
         /* VSEL=10(def) DATSEL=10 (use right ADC only) */
-        wmcodec_write(0x17, 0xc8);                 /* Additional control(1) */
+        wmcodec_write(0x17, 0xc9);                 /* Additional control(1) */
 
         /* VROI=1 (sets output resistance to 40kohms) */
         wmcodec_write(0x1b, 0x40);                 /* Additional control(3) */
@@ -277,7 +285,7 @@ void audiohw_enable_recording(bool source_mic)
         wmcodec_write(0x21, 0x60);               /* ADCR signal path */
     } else {
         /* VSEL=10(def) DATSEL=00 (left->left, right->right) */
-        wmcodec_write(0x17, 0xc0);                 /* Additional control(1) */
+        wmcodec_write(0x17, 0xc1);                 /* Additional control(1) */
 
         /* VROI=1 (sets output resistance to 40kohms) */
         wmcodec_write(0x1b, 0x40);                 /* Additional control(3) */