From e872e9b91304262717218f93fd31f417d557588b Mon Sep 17 00:00:00 2001
From: Michael Sparmann <theseven@rockbox.org>
Date: Sat, 13 Nov 2010 11:38:38 +0000
Subject: iPod Nano 2G: Reduce popping noise during codec powerup, especially
 when driving high-impedance loads

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@28572 a1c6a512-1295-4272-9138-f99709370657
---
 firmware/drivers/audio/wm8975.c | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

(limited to 'firmware/drivers')

diff --git a/firmware/drivers/audio/wm8975.c b/firmware/drivers/audio/wm8975.c
index 1def644f33..77d567d6da 100644
--- a/firmware/drivers/audio/wm8975.c
+++ b/firmware/drivers/audio/wm8975.c
@@ -53,7 +53,15 @@ static unsigned short wm8975_regs[] =
     [LINVOL]   = LINVOL_LZCEN | 23, /* 0dB */
     [RINVOL]   = RINVOL_RIVU | RINVOL_RZCEN | 23, /* 0dB */
     [DAPCTRL]  = DAPCTRL_DACMU,
+/* This reduces the popping noise during codec powerup
+   noticably, especially with high-impedance loads.
+   We might want to change this for all targets,
+   but it has only been tested on iPod Nano 2G so far. */
+#ifdef IPOD_NANO2G
+    [PWRMGMT1] = PWRMGMT1_VMIDSEL_500K | PWRMGMT1_VREF,
+#else
     [PWRMGMT1] = PWRMGMT1_VMIDSEL_5K | PWRMGMT1_VREF,
+#endif
     [PWRMGMT2] = PWRMGMT2_DACL | PWRMGMT2_DACR | PWRMGMT2_LOUT1 
                  | PWRMGMT2_ROUT1 | PWRMGMT2_LOUT2 | PWRMGMT2_ROUT2,
 };
@@ -126,6 +134,37 @@ static void audiohw_mute(bool mute)
 
 #define IPOD_PCM_LEVEL 0x65       /* -6dB */
 
+/* This reduces the popping noise during codec powerup
+   noticably, especially with high-impedance loads.
+   We might want to change this for all targets,
+   but it has only been tested on iPod Nano 2G so far. */
+#ifdef IPOD_NANO2G
+void audiohw_preinit(void)
+{
+    wmcodec_write(RESET, RESET_RESET);
+
+    wmcodec_write(AINTFCE, AINTFCE_MS | AINTFCE_LRP_I2S_RLO
+                         | AINTFCE_IWL_16BIT | AINTFCE_FORMAT_I2S);
+
+#ifndef IPOD_NANO2G
+    wmcodec_write(SAMPCTRL, WM8975_44100HZ);
+#endif
+
+    wmcodec_write(LOUTMIX1, LOUTMIX1_LD2LO | LOUTMIX1_LI2LOVOL(5));
+    wmcodec_write(ROUTMIX2, ROUTMIX2_RD2RO | ROUTMIX2_RI2ROVOL(5));
+
+    wm8975_write(PWRMGMT1, wm8975_regs[PWRMGMT1]);
+    wm8975_write(PWRMGMT2, wm8975_regs[PWRMGMT2]);
+}
+
+void audiohw_postinit(void)
+{
+    wm8975_regs[PWRMGMT1] &= ~PWRMGMT1_VMIDSEL_MASK;
+    wm8975_regs[PWRMGMT1] |= PWRMGMT1_VMIDSEL_50K;
+    wm8975_write(PWRMGMT1, wm8975_regs[PWRMGMT1]);
+    audiohw_mute(false);
+}
+#else
 void audiohw_preinit(void)
 {
     /* POWER UP SEQUENCE */
@@ -170,7 +209,7 @@ void audiohw_postinit(void)
 {
     audiohw_mute(false);
 }
-
+#endif
 
 void audiohw_set_master_vol(int vol_l, int vol_r)
 {
-- 
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