WM8904: Add logic to analyze BCLK setup

6 files changed, 358 insertions, 109 deletions

diff --git a/nuttx/drivers/audio/Kconfig b/nuttx/drivers/audio/Kconfig
index b226e2f04..e0fdf4e2b 100644
--- a/nuttx/drivers/audio/Kconfig
+++ b/nuttx/drivers/audio/Kconfig
@@ -137,6 +137,12 @@ config WM8904_REGDUMP
 	---help---
 		Enable logic to dump the contents of all WM8904 registers.
 
+config WM8904_CLKDEBUG
+	bool "WM8904 clock analysis"
+	default n
+	---help---
+		Enable logic to analyze WM8904 clock configuation.
+
 endif # AUDIO_WM8904
 
 config AUDIO_NULL
diff --git a/nuttx/drivers/audio/Make.defs b/nuttx/drivers/audio/Make.defs
index 049882967..f645deade 100644
--- a/nuttx/drivers/audio/Make.defs
+++ b/nuttx/drivers/audio/Make.defs
@@ -47,6 +47,10 @@ ifeq ($(CONFIG_AUDIO_WM8904),y)
 CSRCS += wm8904.c
 ifeq ($(CONFIG_WM8904_REGDUMP),y)
 CSRCS += wm8904_debug.c
+else
+ifeq ($(CONFIG_WM8904_CLKDEBUG),y)
+CSRCS += wm8904_debug.c
+endif
 endif
 endif
 
diff --git a/nuttx/drivers/audio/wm8904.c b/nuttx/drivers/audio/wm8904.c
index 3cb3f0c97..90fe08952 100644
--- a/nuttx/drivers/audio/wm8904.c
+++ b/nuttx/drivers/audio/wm8904.c
@@ -75,99 +75,15 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
-/* Dummy register address */
-
-#define WM8904_DUMMY              0xff
-
-/* Default FLL configuration */
-
-#define WM8904_DEFAULT_SAMPRATE   11025
-#define WM8904_DEFAULT_NCHANNELS  1
-#define WM8904_DEFAULT_BPSAMP     16
-
-#define WM8904_STARTBITS          2
-
-#define WM8904_NFLLRATIO_DIV1     0
-#define WM8904_NFLLRATIO_DIV2     1
-#define WM8904_NFLLRATIO_DIV4     2
-#define WM8904_NFLLRATIO_DIV8     3
-#define WM8904_NFLLRATIO_DIV16    4
-#define WM8904_NFLLRATIO          5
-
-#define WM8904_MINOUTDIV          4
-#define WM8904_MAXOUTDIV          64
-
-#define WM8904_BCLK_MAXDIV        20
-
-#define WM8904_FVCO_MIN           90000000
-#define WM8904_FVCO_MAX           100000000
-
-/* Commonly defined and redefined macros */
-
-#ifndef MIN
-#  define MIN(a,b) (((a) < (b)) ? (a) : (b))
-#endif
-
-#ifndef MAX
-#  define MAX(a,b) (((a) > (b)) ? (a) : (b))
-#endif
-
 /****************************************************************************
  * Private Types
  ****************************************************************************/
 
-struct wm8904_dev_s
-{
-  /* We are an audio lower half driver (We are also the upper "half" of
-   * the WM8904 driver with respect to the board lower half driver).
-   *
-   * Terminology: Our "lower" half audio instances will be called dev for the
-   * publicly visible version and "priv" for the version that only this driver
-   * knows.  From the point of view of this driver, it is the board lower
-   * "half" that is referred to as "lower".
-   */
-
-  struct audio_lowerhalf_s dev;             /* WM8904 audio lower half (this device) */
-
-  /* Our specific driver data goes here */
-
-  const FAR struct wm8904_lower_s *lower;   /* Pointer to the board lower functions */
-  FAR struct i2c_dev_s   *i2c;              /* I2C driver to use */
-  FAR struct i2s_dev_s   *i2s;              /* I2S driver to use */
-  struct dq_queue_s       pendq;            /* Queue of pending buffers to be sent */
-  struct dq_queue_s       doneq;            /* Queue of sent buffers to be returned */
-  mqd_t                   mq;               /* Message queue for receiving messages */
-  char                    mqname[16];       /* Our message queue name */
-  pthread_t               threadid;         /* ID of our thread */
-  uint32_t                bitrate;          /* Actual programmed bit rate */
-  sem_t                   pendsem;          /* Protect pendq */
-  uint16_t                samprate;         /* Configured samprate (samples/sec) */
-#ifndef CONFIG_AUDIO_EXCLUDE_VOLUME
-#ifndef CONFIG_AUDIO_EXCLUDE_BALANCE
-  uint16_t                balance;          /* Current balance level (b16) */
-#endif  /* CONFIG_AUDIO_EXCLUDE_BALANCE */
-  uint8_t                 volume;           /* Current volume level {0..63} */
-#endif  /* CONFIG_AUDIO_EXCLUDE_VOLUME */
-  uint8_t                 nchannels;        /* Number of channels (1 or 2) */
-  uint8_t                 bpsamp;           /* Bits per sample (8 or 16) */
-  volatile uint8_t        inflight;         /* Number of audio buffers in-flight */
-  bool                    running;          /* True: Worker thread is running */
-  bool                    paused;           /* True: Playing is paused */
-  bool                    mute;             /* True: Output is muted */
-#ifndef CONFIG_AUDIO_EXCLUDE_STOP
-  bool                    terminating;      /* True: Stop requested */
-#endif
-  bool                    reserved;         /* True: Device is reserved */
-  volatile int            result;           /* The result of the last transfer */
-};
-
-static const uint8_t g_fllratio[WM8904_NFLLRATIO] = {1, 2, 4, 8, 16};
-
 /****************************************************************************
  * Private Function Prototypes
  ****************************************************************************/
 
-#ifndef CONFIG_WM8904_REGDUMP
+#if !defined(CONFIG_WM8904_REGDUMP) && !defined(CONFIG_WM8904_CLKDEBUG)
 static
 #endif
        uint16_t wm8904_readreg(FAR struct wm8904_dev_s *priv,
@@ -289,13 +205,21 @@ static const struct audio_ops_s g_audioops =
   wm8904_release        /* release        */
 };
 
-static const uint8_t g_sysclk_scaleb1[WM8904_BCLK_MAXDIV+1] =
+#ifndef CONFIG_WM8904_CLKDEBUG
+static
+#endif
+const uint8_t g_sysclk_scaleb1[WM8904_BCLK_MAXDIV+1] =
 {
    2,  3,  4,  6,  8, 10, 11, /*  1,  1.5,  2,  3,  4,  5,  5.5 */
   12, 16, 20, 22, 24, 32, 40, /*  6,  8,   10, 11, 12, 16, 20   */
   44, 48, 50, 60, 64, 88, 96  /* 22, 24,   25, 30, 32, 44, 48   */
 };
 
+#ifndef CONFIG_WM8904_CLKDEBUG
+static
+#endif
+const uint8_t g_fllratio[WM8904_NFLLRATIO] = {1, 2, 4, 8, 16};
+
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
@@ -308,7 +232,7 @@ static const uint8_t g_sysclk_scaleb1[WM8904_BCLK_MAXDIV+1] =
  *
  ****************************************************************************/
 
-#ifndef CONFIG_WM8904_REGDUMP
+#if !defined(CONFIG_WM8904_REGDUMP) && !defined(CONFIG_WM8904_CLKDEBUG)
 static
 #endif
 uint16_t wm8904_readreg(FAR struct wm8904_dev_s *priv, uint8_t regaddr)
@@ -900,7 +824,7 @@ static void wm8904_setbitrate(FAR struct wm8904_dev_s *priv)
    *
    * Already set above
    */
- 
+
   /* Allow time for FLL lock.  Typical is 2 MSec.  Lock status is available
    * in the WM8904 interrupt status register.
    */
@@ -911,19 +835,6 @@ static void wm8904_setbitrate(FAR struct wm8904_dev_s *priv)
 
   regval = WM8904_FLL_FRACN_ENA | WM8904_FLL_ENA;
   wm8904_writereg(priv, WM8904_FLL_CTRL1, regval);
-
-  /* Dump all FLL registers */
-
-  audvdbg("FLL control 1[%02x]: %04x\n",
-          WM8904_FLL_CTRL1, wm8904_readreg(priv, WM8904_FLL_CTRL1));
-  audvdbg("FLL control 2[%02x]: %04x\n",
-          WM8904_FLL_CTRL2, wm8904_readreg(priv, WM8904_FLL_CTRL2));
-  audvdbg("FLL control 3[%02x]: %04x\n",
-          WM8904_FLL_CTRL3, wm8904_readreg(priv, WM8904_FLL_CTRL3));
-  audvdbg("FLL control 4[%02x]: %04x\n",
-          WM8904_FLL_CTRL4, wm8904_readreg(priv, WM8904_FLL_CTRL4));
-  audvdbg("FLL control 5[%02x]: %04x\n",
-          WM8904_FLL_CTRL5, wm8904_readreg(priv, WM8904_FLL_CTRL5));
 }
 
 /****************************************************************************
@@ -1260,6 +1171,8 @@ static int wm8904_configure(FAR struct audio_lowerhalf_s *dev,
         wm8904_setbitrate(priv);
         wm8904_setlrclock(priv);
         wm8904_writereg(priv, WM8904_DUMMY, 0x55aa);
+
+        wm8904_clock_analysis(&priv->dev, "AUDIO_TYPE_OUTPUT");
         ret = OK;
       }
       break;
@@ -2375,6 +2288,7 @@ FAR struct audio_lowerhalf_s *
 
       wm8904_audio_output(priv);
       wm8904_dump_registers(&priv->dev, "After configuration");
+      wm8904_clock_analysis(&priv->dev, "After configuration");
 
       /* Attach our ISR to this device */
 
diff --git a/nuttx/drivers/audio/wm8904.h b/nuttx/drivers/audio/wm8904.h
index 41f2e3699..9b2059c6c 100644
--- a/nuttx/drivers/audio/wm8904.h
+++ b/nuttx/drivers/audio/wm8904.h
@@ -47,6 +47,9 @@
 #include <nuttx/config.h>
 #include <nuttx/compiler.h>
 
+#include <pthread.h>
+#include <mqueue.h>
+
 #include <nuttx/fs/ioctl.h>
 
 #ifdef CONFIG_AUDIO
@@ -157,6 +160,8 @@
 #define WM8904_FLL_NCO_TEST0         0xf7 /* FLL NCO Test 0 */
 #define WM8904_FLL_NCO_TEST1         0xf8 /* FLL NCO Test 1 */
 
+#define WM8904_DUMMY                 0xff /* Dummy register address */
+
 /* Register Default Values **************************************************/
 /* Registers have some undocumented bits set on power up.  These probably
  * should be retained on writes (?).
@@ -853,7 +858,7 @@
 #  define WM8904_FLL_CLK_REF_DIV4    (2 << WM8904_FLL_CLK_REF_DIV_SHIFT) /* MCLK / 4 */
 #  define WM8904_FLL_CLK_REF_DIV8    (3 << WM8904_FLL_CLK_REF_DIV_SHIFT) /* MCLK / 8 */
 #define WM8904_FLL_CLK_REF_SRC_SHIFT   (0)      /* Bits 0-2: FLL clock source */
-#define WM8904_FLL_CLK_REF_SRC_MASK    (3) << WM8904_FLL_CLK_REF_SRC_SHIFT)
+#define WM8904_FLL_CLK_REF_SRC_MASK    (3 << WM8904_FLL_CLK_REF_SRC_SHIFT)
 #  define WM8904_FLL_CLK_REF_SRC_MCLK  (0 << WM8904_FLL_CLK_REF_SRC_SHIFT)
 #  define WM8904_FLL_CLK_REF_SRC_BCLK  (1 << WM8904_FLL_CLK_REF_SRC_SHIFT)
 #  define WM8904_FLL_CLK_REF_SRC_LRCLK (2 << WM8904_FLL_CLK_REF_SRC_SHIFT)
@@ -977,14 +982,98 @@
 
 /* 0xf8 FLL NCO Test 1 (16-bit FLL forced oscillator value */
 
+/* FLL Configuration *********************************************************/
+/* Default FLL configuration */
+
+#define WM8904_DEFAULT_SAMPRATE      11025
+#define WM8904_DEFAULT_NCHANNELS     1
+#define WM8904_DEFAULT_BPSAMP        16
+
+#define WM8904_STARTBITS             2
+
+#define WM8904_NFLLRATIO_DIV1        0
+#define WM8904_NFLLRATIO_DIV2        1
+#define WM8904_NFLLRATIO_DIV4        2
+#define WM8904_NFLLRATIO_DIV8        3
+#define WM8904_NFLLRATIO_DIV16       4
+#define WM8904_NFLLRATIO             5
+
+#define WM8904_MINOUTDIV             4
+#define WM8904_MAXOUTDIV             64
+
+#define WM8904_BCLK_MAXDIV           20
+
+#define WM8904_FVCO_MIN              90000000
+#define WM8904_FVCO_MAX              100000000
+
+/* Commonly defined and redefined macros */
+
+#ifndef MIN
+#  define MIN(a,b)                   (((a) < (b)) ? (a) : (b))
+#endif
+
+#ifndef MAX
+#  define MAX(a,b)                   (((a) > (b)) ? (a) : (b))
+#endif
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/
 
+struct wm8904_dev_s
+{
+  /* We are an audio lower half driver (We are also the upper "half" of
+   * the WM8904 driver with respect to the board lower half driver).
+   *
+   * Terminology: Our "lower" half audio instances will be called dev for the
+   * publicly visible version and "priv" for the version that only this driver
+   * knows.  From the point of view of this driver, it is the board lower
+   * "half" that is referred to as "lower".
+   */
+
+  struct audio_lowerhalf_s dev;             /* WM8904 audio lower half (this device) */
+
+  /* Our specific driver data goes here */
+
+  const FAR struct wm8904_lower_s *lower;   /* Pointer to the board lower functions */
+  FAR struct i2c_dev_s   *i2c;              /* I2C driver to use */
+  FAR struct i2s_dev_s   *i2s;              /* I2S driver to use */
+  struct dq_queue_s       pendq;            /* Queue of pending buffers to be sent */
+  struct dq_queue_s       doneq;            /* Queue of sent buffers to be returned */
+  mqd_t                   mq;               /* Message queue for receiving messages */
+  char                    mqname[16];       /* Our message queue name */
+  pthread_t               threadid;         /* ID of our thread */
+  uint32_t                bitrate;          /* Actual programmed bit rate */
+  sem_t                   pendsem;          /* Protect pendq */
+  uint16_t                samprate;         /* Configured samprate (samples/sec) */
+#ifndef CONFIG_AUDIO_EXCLUDE_VOLUME
+#ifndef CONFIG_AUDIO_EXCLUDE_BALANCE
+  uint16_t                balance;          /* Current balance level (b16) */
+#endif  /* CONFIG_AUDIO_EXCLUDE_BALANCE */
+  uint8_t                 volume;           /* Current volume level {0..63} */
+#endif  /* CONFIG_AUDIO_EXCLUDE_VOLUME */
+  uint8_t                 nchannels;        /* Number of channels (1 or 2) */
+  uint8_t                 bpsamp;           /* Bits per sample (8 or 16) */
+  volatile uint8_t        inflight;         /* Number of audio buffers in-flight */
+  bool                    running;          /* True: Worker thread is running */
+  bool                    paused;           /* True: Playing is paused */
+  bool                    mute;             /* True: Output is muted */
+#ifndef CONFIG_AUDIO_EXCLUDE_STOP
+  bool                    terminating;      /* True: Stop requested */
+#endif
+  bool                    reserved;         /* True: Device is reserved */
+  volatile int            result;           /* The result of the last transfer */
+};
+
 /****************************************************************************
  * Public Data
  ****************************************************************************/
 
+#ifdef CONFIG_WM8904_CLKDEBUG
+extern const uint8_t g_sysclk_scaleb1[WM8904_BCLK_MAXDIV+1];
+extern const uint8_t g_fllratio[WM8904_NFLLRATIO];
+#endif
+
 /****************************************************************************
  * Public Function Prototypes
  ****************************************************************************/
@@ -997,7 +1086,7 @@
  *
  ****************************************************************************/
 
-#ifdef CONFIG_WM8904_REGDUMP
+#if defined(CONFIG_WM8904_REGDUMP) || defined(CONFIG_WM8904_CLKDEBUG)
 struct wm8904_dev_s;
 uint16_t wm8904_readreg(FAR struct wm8904_dev_s *priv, uint8_t regaddr);
 #endif
diff --git a/nuttx/drivers/audio/wm8904_debug.c b/nuttx/drivers/audio/wm8904_debug.c
index df6e9abb2..753712827 100644
--- a/nuttx/drivers/audio/wm8904_debug.c
+++ b/nuttx/drivers/audio/wm8904_debug.c
@@ -48,14 +48,15 @@
 #include <nuttx/config.h>
 
 #include <stdint.h>
+#include <assert.h>
+#include <fixedmath.h>
 #include <syslog.h>
 
 #include <nuttx/audio/audio.h>
+#include <nuttx/audio/wm8904.h>
 
 #include "wm8904.h"
 
-#ifdef CONFIG_WM8904_REGDUMP
-
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -64,11 +65,13 @@
  * Private Types
  ****************************************************************************/
 
-struct wm8904_debug_s
+#ifdef CONFIG_WM8904_REGDUMP
+struct wb8904_regdump_s
 {
   FAR const char *regname;
   uint8_t regaddr;
 };
+#endif
 
 /****************************************************************************
  * Private Function Prototypes
@@ -78,7 +81,8 @@ struct wm8904_debug_s
  * Private Data
  ****************************************************************************/
 
-static const struct wm8904_debug_s g_wm8904_debug[] =
+#ifdef CONFIG_WM8904_REGDUMP
+static const struct wb8904_regdump_s g_wm8904_debug[] =
 {
   {"ID",              WM8904_ID              },
   {"BIAS_CTRL",       WM8904_BIAS_CTRL       },
@@ -180,7 +184,8 @@ static const struct wm8904_debug_s g_wm8904_debug[] =
   {"FLL_NCO_TEST1",   WM8904_FLL_NCO_TEST1   }
 };
 
-#define WM8904_NREGISTERS (sizeof(g_wm8904_debug)/sizeof(struct wm8904_debug_s))
+#  define WM8904_NREGISTERS (sizeof(g_wm8904_debug)/sizeof(struct wb8904_regdump_s))
+#endif /* CONFIG_WM8904_REGDUMP */
 
 /****************************************************************************
  * Private Functions
@@ -204,6 +209,7 @@ static const struct wm8904_debug_s g_wm8904_debug[] =
  *
  ****************************************************************************/
 
+#ifdef CONFIG_WM8904_REGDUMP
 void wm8904_dump_registers(FAR struct audio_lowerhalf_s *dev,
                            FAR const char *msg)
 {
@@ -218,5 +224,210 @@ void wm8904_dump_registers(FAR struct audio_lowerhalf_s *dev,
                             g_wm8904_debug[i].regaddr));
     }
 }
-
 #endif /* CONFIG_WM8904_REGDUMP */
+
+/****************************************************************************
+ * Name: wm8904_clock_analysis
+ *
+ * Description:
+ *   Analyze the settings in the clock chain and dump to syslog.
+ *
+ * Input Parameters:
+ *   dev - The device instance returned by wm8904_initialize
+ *
+ * Returned Value:
+ *   None.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_WM8904_CLKDEBUG
+void wm8904_clock_analysis(FAR struct audio_lowerhalf_s *dev,
+                           FAR const char *msg)
+{
+  FAR struct wm8904_dev_s *priv = (FAR struct wm8904_dev_s *)dev;
+  uint32_t sysclk;
+  uint32_t bclk;
+  uint32_t lrclk;
+  uint16_t regval;
+  unsigned int tmp;
+  double ftmp;
+
+  syslog("WM8904 Clock Analysis: %s\n", msg);
+  DEBUGASSERT(priv && priv->lower);
+  syslog("  MCLK:            %lu Hz\n", (unsigned long)priv->lower->mclk);
+
+  /* Is the SYSCLK source the FLL?  Or MCK? */
+
+  regval = wm8904_readreg(priv, WM8904_CLKRATE2);
+  if ((regval & WM8904_SYSCLK_SRC) == WM8904_SYSCLK_SRCMCLK)
+    {
+      /* The SYSCLK divider bypasses the FLL and takes its input
+       * directly from MCLK.
+       */
+
+      sysclk = priv->lower->mclk;
+      syslog("  SYSCLK Source:   MCLK (%s)\n",
+             (regval & WM8904_MCLK_INV) != 0 ? "inverted" : "not inverted");
+    }
+  else
+    {
+      uint32_t fref;
+      uint32_t fvco;
+      uint32_t fout;
+      unsigned int outdiv;
+      unsigned int frndx;
+      unsigned int flln;
+      unsigned int fllk;
+      unsigned int fratio;
+      double nk;
+
+      /* Assume that the Fref input to the FLL is MCLK */
+
+      fref = priv->lower->mclk;
+
+      /* Now get the real FLL input source */
+
+      regval = wm8904_readreg(priv, WM8904_FLL_CTRL5);
+      switch (regval & WM8904_FLL_CLK_REF_SRC_MASK)
+        {
+          case WM8904_FLL_CLK_REF_SRC_MCLK:
+            syslog("  FLL Source:      MCLK\n");
+            break;
+
+          case WM8904_FLL_CLK_REF_SRC_BCLK:
+            syslog("  ERROR: FLL source is BCLK: %04x\n", regval);
+            break;
+
+          case WM8904_FLL_CLK_REF_SRC_LRCLK:
+            syslog("  ERROR: FLL source is LRCLK: %04x\n", regval);
+            break;
+
+          default:
+            syslog("  ERROR: Unrecognized FLL source: %04x\n", regval);
+        }
+
+      syslog("  Fref:            %lu Hz (before divider)\n", fref);
+      switch (regval & WM8904_FLL_CLK_REF_DIV_MASK)
+        {
+          case WM8904_FLL_CLK_REF_DIV1:
+            syslog("  FLL_CLK_REF_DIV: 1\n");
+            break;
+
+          case WM8904_FLL_CLK_REF_DIV2:
+            syslog("  FLL_CLK_REF_DIV: 2\n");
+            fref >>= 1;
+            break;
+
+          case WM8904_FLL_CLK_REF_DIV4:
+            syslog("  FLL_CLK_REF_DIV: 4\n");
+            fref >>= 2;
+            break;
+
+          case WM8904_FLL_CLK_REF_DIV8:
+            syslog("  FLL_CLK_REF_DIV: 8\n");
+            fref >>= 3;
+            break;
+        }
+
+      syslog("  Fref:            %lu Hz (after divider)\n", fref);
+
+      regval = wm8904_readreg(priv, WM8904_FLL_CTRL2);
+      frndx  = (regval & WM8904_FLL_FRATIO_MASK) >> WM8904_FLL_FRATIO_SHIFT;
+      tmp    = (regval & WM8904_FLL_CTRL_RATE_MASK) >> WM8904_FLL_CTRL_RATE_SHIFT;
+      outdiv = ((regval & WM8904_FLL_OUTDIV_MASK) >> WM8904_FLL_OUTDIV_SHIFT) + 1;
+
+      syslog("  FLL_CTRL_RATE:   Fvco / %u\n", tmp + 1);
+
+      regval = wm8904_readreg(priv, WM8904_FLL_CTRL4);
+      flln   = (regval & WM8904_FLL_N_MASK) >> WM8904_FLL_N_SHIFT;
+      tmp    = (regval & WM8904_FLL_GAIN_MASK) >> WM8904_FLL_GAIN_SHIFT;
+
+      syslog("  FLL_GAIN:        %u\n", (1 << tmp));
+
+      fllk   = wm8904_readreg(priv, WM8904_FLL_CTRL3);
+      nk     = (double)flln + ((double)fllk / 65536.0);
+      fratio = g_fllratio[frndx];
+
+      syslog("  FLL_FRATIO:      %u\n", fratio);
+      syslog("  FLL_OUTDIV:      %u\n", outdiv);
+      syslog("  FLL_N.K:         %u.%05u\n", flln, fllk);
+
+      ftmp = nk * (double)fref * (double)fratio;
+      fvco = (uint32_t)ftmp;
+
+      syslog("  Fvco:            %lu Hz\n", (unsigned long)fvco);
+
+      fout = fvco / outdiv;
+      syslog("  Fout:            %lu Hz\n", (unsigned long)fout);
+
+      regval = wm8904_readreg(priv, WM8904_FLL_CTRL1);
+
+      syslog("  FLL_FRACN_ENA:   %s\n",
+             (regval & WM8904_FLL_FRACN_ENA) != 0 ? "Enabled" : "Disabled");
+      syslog("  FLL_OSC_ENA:     %s\n",
+             (regval & WM8904_FLL_OSC_ENA) != 0 ? "Enabled" : "Disabled");
+      syslog("  FLL_ENA:         %s\n",
+             (regval & WM8904_FLL_ENA) != 0 ? "Enabled" : "Disabled");
+
+      if ((regval & WM8904_FLL_ENA) == 0)
+        {
+          syslog("  No SYSCLK\n");
+          return;
+        }
+
+      sysclk = fout;
+    }
+
+  syslog("  SYSCLK:          %lu Hz (before divider)\n", (unsigned long)sysclk);
+
+  regval = wm8904_readreg(priv, WM8904_CLKRATE0);
+  if ((regval & WM8904_MCLK_DIV) == WM8904_MCLK_DIV1)
+    {
+      syslog("  MCLK_DIV:        1\n");
+    }
+  else
+    {
+      syslog("  MCLK_DIV:        2\n");
+      sysclk >>=1;
+    }
+
+  syslog("  SYSCLK:          %lu (after divider)\n", (unsigned long)sysclk);
+
+  regval = wm8904_readreg(priv, WM8904_CLKRATE2);
+
+  syslog("  CLK_SYS_ENA:     %s\n",
+         (regval & WM8904_CLK_SYS_ENA) != 0 ? "Enabled" : "Disabled");
+
+  if ((regval & WM8904_CLK_SYS_ENA) == 0)
+    {
+      syslog("  No SYSCLK\n");
+      return;
+    }
+
+  regval = wm8904_readreg(priv, WM8904_AIF2);
+  tmp    = (regval & WM8904_BCLK_DIV_MASK) >> WM8904_BCLK_DIV_SHIFT;
+  tmp    = g_sysclk_scaleb1[tmp];
+  ftmp   = (double)tmp / 2.0;
+
+  syslog("  BCLK_DIV:        SYSCLK / %u.%01u\n",
+         (unsigned int)(tmp >> 1), (unsigned int)(5 * (tmp & 1)));
+
+  bclk = (uint32_t)(sysclk / ftmp);
+
+  syslog("  BCLK:            %lu Hz\n", (unsigned long)bclk);
+
+  regval = wm8904_readreg(priv, WM8904_AIF1);
+  syslog("  BCLK_DIR:        %s\n",
+         (regval & WM8904_BCLK_DIR) != 0 ? "Output" : "Input");
+
+  regval = wm8904_readreg(priv, WM8904_AIF3);
+  tmp = (regval & WM8904_LRCLK_RATE_MASK) >> WM8904_LRCLK_RATE_SHIFT;
+
+  lrclk = bclk / tmp;
+
+  syslog("  LRCLK_RATE:      BCLK / %lu\n", (unsigned long)tmp);
+  syslog("  LRCLK:           %lu\n", (unsigned long)lrclk);
+  syslog("  LRCLK_DIR:       %s\n",
+         (regval & WM8904_LRCLK_DIR) != 0 ? "Output" : "Input");
+}
+#endif /* CONFIG_WM8904_CLKDEBUG */
diff --git a/nuttx/include/nuttx/audio/wm8904.h b/nuttx/include/nuttx/audio/wm8904.h
index 9c25fd4ad..c2f0a78ed 100644
--- a/nuttx/include/nuttx/audio/wm8904.h
+++ b/nuttx/include/nuttx/audio/wm8904.h
@@ -245,6 +245,31 @@ void wm8904_dump_registers(FAR struct audio_lowerhalf_s *dev,
 #  define wm8904_dump_registers(d,m)
 #endif
 
+/****************************************************************************
+ * Name: wm8904_clock_analysis
+ *
+ * Description:
+ *   Analyze the settings in the clock chain and dump to syslog.
+ *
+ * Input Parameters:
+ *   dev - The device instance returned by wm8904_initialize
+ *
+ * Returned Value:
+ *   None.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_WM8904_CLKDEBUG
+void wm8904_clock_analysis(FAR struct audio_lowerhalf_s *dev,
+                           FAR const char *msg);
+#else
+  /* This eliminates the need for any conditional compilation in the
+   * including file.
+   */
+
+#  define wm8904_clock_analysis(d,m)
+#endif
+
 #undef EXTERN
 #ifdef __cplusplus
 }