Revise the PCM callback system after adding multichannel audio.

Additional status callback is added to pcm_play/rec_data instead of
using a special function to set it. Status includes DMA error
reporting to the status callback. Playback and recording callback
become more alike except playback uses "const void **addr" (because
the data should not be altered) and recording  uses "void **addr".
"const" is put in place throughout where appropriate.

Most changes are fairly trivial. One that should be checked in
particular because it isn't so much is telechips, if anyone cares to
bother. PP5002 is not so trivial either but that tested as working.

Change-Id: I4928d69b3b3be7fb93e259f81635232df9bd1df2
Reviewed-on: http://gerrit.rockbox.org/166
Reviewed-by: Michael Sevakis <jethead71@rockbox.org>
Tested-by: Michael Sevakis <jethead71@rockbox.org>

48 files changed, 765 insertions, 718 deletions

diff --git a/apps/beep.c b/apps/beep.c
index d3345afdf9..3b02e5d8a3 100644
--- a/apps/beep.c
+++ b/apps/beep.c
@@ -46,7 +46,7 @@ static int16_t beep_buf[BEEP_BUF_COUNT*2] IBSS_ATTR __attribute__((aligned(4)));
 /* Callback to generate the beep frames - also don't want inlining of
    call below in beep_play */
 static void __attribute__((noinline))
-beep_get_more(unsigned char **start, size_t *size)
+beep_get_more(const void **start, size_t *size)
 {
     int count = beep_count;
 
@@ -87,7 +87,7 @@ void beep_play(unsigned int frequency, unsigned int duration,
 #endif
 
     /* If it fits - avoid cb overhead */
-    unsigned char *start;
+    const void *start;
     size_t size;
 
     /* Generate first frame here */
diff --git a/apps/pcmbuf.c b/apps/pcmbuf.c
index e0bfa1f62a..7ba4eeef8e 100644
--- a/apps/pcmbuf.c
+++ b/apps/pcmbuf.c
@@ -694,7 +694,7 @@ void pcmbuf_start_track_change(enum pcm_track_change_type type)
 /** Playback */
 
 /* PCM driver callback */
-static void pcmbuf_pcm_callback(unsigned char **start, size_t *size)
+static void pcmbuf_pcm_callback(const void **start, size_t *size)
 {
     /*- Process the chunk that just finished -*/
     size_t index = chunk_ridx;
diff --git a/apps/plugin.h b/apps/plugin.h
index 2fb085de6d..e07ec92c08 100644
--- a/apps/plugin.h
+++ b/apps/plugin.h
@@ -153,12 +153,12 @@ void* plugin_get_buffer(size_t *buffer_size);
 #define PLUGIN_MAGIC 0x526F634B /* RocK */
 
 /* increase this every time the api struct changes */
-#define PLUGIN_API_VERSION 216
+#define PLUGIN_API_VERSION 217
 
 /* update this to latest version if a change to the api struct breaks
    backwards compatibility (and please take the opportunity to sort in any
    new function which are "waiting" at the end of the function table) */
-#define PLUGIN_MIN_API_VERSION 216
+#define PLUGIN_MIN_API_VERSION 217
 
 /* plugin return codes */
 /* internal returns start at 0x100 to make exit(1..255) work */
@@ -651,7 +651,8 @@ struct plugin_api {
     const unsigned long *hw_freq_sampr;
     void (*pcm_apply_settings)(void);
     void (*pcm_play_data)(pcm_play_callback_type get_more,
-            unsigned char* start, size_t size);
+                          pcm_status_callback_type status_cb,
+                          const void *start, size_t size);
     void (*pcm_play_stop)(void);
     void (*pcm_set_frequency)(unsigned int frequency);
     bool (*pcm_is_playing)(void);
@@ -669,6 +670,7 @@ struct plugin_api {
     void (*pcm_init_recording)(void);
     void (*pcm_close_recording)(void);
     void (*pcm_record_data)(pcm_rec_callback_type more_ready,
+                            pcm_status_callback_type status_cb,
                             void *start, size_t size);
     void (*pcm_stop_recording)(void);
     void (*pcm_calculate_rec_peaks)(int *left, int *right);
@@ -689,12 +691,13 @@ struct plugin_api {
     int (*dsp_output_count)(struct dsp_config *dsp, int count);
 
     enum channel_status (*mixer_channel_status)(enum pcm_mixer_channel channel);
-    void * (*mixer_channel_get_buffer)(enum pcm_mixer_channel channel, int *count);
+    const void * (*mixer_channel_get_buffer)(enum pcm_mixer_channel channel,
+                                             int *count);
     void (*mixer_channel_calculate_peaks)(enum pcm_mixer_channel channel,
                                           int *left, int *right);
     void (*mixer_channel_play_data)(enum pcm_mixer_channel channel,
                                     pcm_play_callback_type get_more,
-                                    unsigned char *start, size_t size);
+                                    const void *start, size_t size);
     void (*mixer_channel_play_pause)(enum pcm_mixer_channel channel, bool play);
     void (*mixer_channel_stop)(enum pcm_mixer_channel channel);
     void (*mixer_channel_set_amplitude)(enum pcm_mixer_channel channel,
diff --git a/apps/plugins/beatbox/beatbox.c b/apps/plugins/beatbox/beatbox.c
index 8ecbabd1e5..8c7413cc99 100644
--- a/apps/plugins/beatbox/beatbox.c
+++ b/apps/plugins/beatbox/beatbox.c
@@ -509,7 +509,7 @@ void redrawScreen(unsigned char force)
     rb->lcd_update();
 }
 
-void get_more(unsigned char** start, size_t* size)
+void get_more(const void** start, size_t* size)
 {
 #ifndef SYNC
     if(lastswap!=swap)
@@ -523,10 +523,10 @@ void get_more(unsigned char** start, size_t* size)
 
     *size = BUF_SIZE*sizeof(short);
 #ifndef SYNC
-    *start = (unsigned char*)((swap ? gmbuf : gmbuf + BUF_SIZE));
+    *start = swap ? gmbuf : gmbuf + BUF_SIZE;
     swap=!swap;
 #else
-    *start = (unsigned char*)(gmbuf);
+    *start = gmbuf;
 #endif
 }
 
@@ -537,7 +537,7 @@ int beatboxmain()
 
     numberOfSamples=44100/10;
     synthbuf();
-    rb->pcm_play_data(&get_more, NULL, 0);
+    rb->pcm_play_data(&get_more, NULL, NULL, 0);
 
     rb->lcd_set_background(0x000000);
     rb->lcd_clear_display();
diff --git a/apps/plugins/doom/i_sound.c b/apps/plugins/doom/i_sound.c
index 2d7b592818..bdf70c1215 100644
--- a/apps/plugins/doom/i_sound.c
+++ b/apps/plugins/doom/i_sound.c
@@ -457,11 +457,11 @@ void I_UpdateSound( void )
 //  only output be done asynchronous?
 //
 
-void get_more(unsigned char** start, size_t* size)
+void get_more(const void** start, size_t* size)
 {
    I_UpdateSound(); // Force sound update
 
-   *start = (unsigned char*)(mixbuffer);
+   *start = mixbuffer;
    *size = SAMPLECOUNT*2*sizeof(short);
 }
 
@@ -471,7 +471,7 @@ void I_SubmitSound(void)
    if (!enable_sound)
       return;
 
-   rb->pcm_play_data(&get_more, NULL, 0);
+   rb->pcm_play_data(&get_more, NULL, NULL, 0);
 }
 
 void I_ShutdownSound(void)
diff --git a/apps/plugins/fft/fft.c b/apps/plugins/fft/fft.c
index 1c4e1b4c20..f7d8943576 100644
--- a/apps/plugins/fft/fft.c
+++ b/apps/plugins/fft/fft.c
@@ -1186,8 +1186,8 @@ static inline bool fft_init_fft_lib(void)
 static inline bool fft_get_fft(void)
 {
     int count;
-    int16_t *value =
-        (int16_t *) rb->mixer_channel_get_buffer(PCM_MIXER_CHAN_PLAYBACK, &count);
+    const int16_t *value =
+        rb->mixer_channel_get_buffer(PCM_MIXER_CHAN_PLAYBACK, &count);
     /* This block can introduce discontinuities in our data. Meaning, the
      * FFT will not be done a continuous segment of the signal. Which can
      * be bad. Or not.
diff --git a/apps/plugins/metronome.c b/apps/plugins/metronome.c
index da035a7688..297405571f 100644
--- a/apps/plugins/metronome.c
+++ b/apps/plugins/metronome.c
@@ -721,7 +721,7 @@ static void prepare_tock(void)
 
 static void play_tock(void)
 {
-    rb->pcm_play_data(NULL,(unsigned char *)sndbuf,sizeof(sndbuf));
+    rb->pcm_play_data(NULL, NULL, sndbuf, sizeof(sndbuf));
 }
 
 #endif /* CONFIG_CODEC != SWCODEC */
diff --git a/apps/plugins/midi/midiplay.c b/apps/plugins/midi/midiplay.c
index 40b4f1c83c..1412d4c742 100644
--- a/apps/plugins/midi/midiplay.c
+++ b/apps/plugins/midi/midiplay.c
@@ -319,7 +319,7 @@ static inline void synthbuf(void)
     samples_in_buf = BUF_SIZE-i;
 }
 
-static void get_more(unsigned char** start, size_t* size)
+static void get_more(const void** start, size_t* size)
 {
 #ifndef SYNC
     if(lastswap != swap)
@@ -333,10 +333,10 @@ static void get_more(unsigned char** start, size_t* size)
 
     *size = samples_in_buf*sizeof(int32_t);
 #ifndef SYNC
-    *start = (unsigned char*)((swap ? gmbuf : gmbuf + BUF_SIZE));
+    *start = swap ? gmbuf : gmbuf + BUF_SIZE;
     swap = !swap;
 #else
-    *start = (unsigned char*)(gmbuf);
+    *start = gmbuf;
 #endif
 }
 
@@ -396,7 +396,7 @@ static int midimain(const void * filename)
     samples_this_second = 0;
 
     synthbuf();
-    rb->pcm_play_data(&get_more, NULL, 0);
+    rb->pcm_play_data(&get_more, NULL, NULL, 0);
 
     while (!quit)
     {
@@ -445,7 +445,7 @@ static int midimain(const void * filename)
                 seekBackward(5);
                 midi_debug("Rewind to %d:%02d\n", playing_time/60, playing_time%60);
                 if (is_playing)
-                    rb->pcm_play_data(&get_more, NULL, 0);
+                    rb->pcm_play_data(&get_more, NULL, NULL, 0);
                 break;
             }
 
@@ -455,7 +455,7 @@ static int midimain(const void * filename)
                 seekForward(5);
                 midi_debug("Skip to %d:%02d\n", playing_time/60, playing_time%60);
                 if (is_playing)
-                    rb->pcm_play_data(&get_more, NULL, 0);
+                    rb->pcm_play_data(&get_more, NULL, NULL, 0);
                 break;
             }
 
@@ -470,7 +470,7 @@ static int midimain(const void * filename)
                 {
                     midi_debug("Playing from %d:%02d\n", playing_time/60, playing_time%60);
                     is_playing = true;
-                    rb->pcm_play_data(&get_more, NULL, 0);
+                    rb->pcm_play_data(&get_more, NULL, NULL, 0);
                 }
                 break;
             }
diff --git a/apps/plugins/mikmod/mikmod.c b/apps/plugins/mikmod/mikmod.c
index a7eeb5019f..eb3be13140 100644
--- a/apps/plugins/mikmod/mikmod.c
+++ b/apps/plugins/mikmod/mikmod.c
@@ -268,7 +268,7 @@ static inline void synthbuf(void)
     VC_WriteBytes(outptr, BUF_SIZE);
 }
 
-void get_more(unsigned char** start, size_t* size)
+void get_more(const void** start, size_t* size)
 {
 #ifndef SYNC
     if (lastswap != swap)
@@ -282,10 +282,10 @@ void get_more(unsigned char** start, size_t* size)
 
     *size = BUF_SIZE;
 #ifndef SYNC
-    *start = (unsigned char*)((swap ? gmbuf : gmbuf + BUF_SIZE));
+    *start = swap ? gmbuf : gmbuf + BUF_SIZE;
     swap = !swap;
 #else
-    *start = (unsigned char*)(gmbuf);
+    *start = gmbuf;
 #endif
 }
 
@@ -660,7 +660,7 @@ int playfile(char* filename)
     {
         display = DISPLAY_INFO;
         Player_Start(module);
-        rb->pcm_play_data(&get_more, NULL, 0);
+        rb->pcm_play_data(&get_more, NULL, NULL, 0);
     }
 
 #ifdef HAVE_ADJUSTABLE_CPU_FREQ
@@ -804,7 +804,7 @@ int playfile(char* filename)
             }
             else
             {
-                rb->pcm_play_data(&get_more, NULL, 0);
+                rb->pcm_play_data(&get_more, NULL, NULL, 0);
             }
             Player_TogglePause();
             break;
diff --git a/apps/plugins/mpegplayer/pcm_output.c b/apps/plugins/mpegplayer/pcm_output.c
index 8db9531049..8694ae4a69 100644
--- a/apps/plugins/mpegplayer/pcm_output.c
+++ b/apps/plugins/mpegplayer/pcm_output.c
@@ -85,7 +85,7 @@ static inline ssize_t pcm_output_bytes_free(void)
 }
 
 /* Audio DMA handler */
-static void get_more(unsigned char **start, size_t *size)
+static void get_more(const void **start, size_t *size)
 {
     ssize_t sz;
 
diff --git a/apps/plugins/pacbox/pacbox.c b/apps/plugins/pacbox/pacbox.c
index 5165ff3047..efba47b576 100644
--- a/apps/plugins/pacbox/pacbox.c
+++ b/apps/plugins/pacbox/pacbox.c
@@ -286,7 +286,7 @@ static int16_t raw_buf[NBSAMPLES] IBSS_ATTR;
 /*
     Audio callback
  */
-static void get_more(unsigned char **start, size_t *size)
+static void get_more(const void **start, size_t *size)
 {
     int32_t *out, *outend;
     int16_t *raw;
@@ -306,7 +306,7 @@ static void get_more(unsigned char **start, size_t *size)
     }
     while (out < outend);
 
-    *start = (unsigned char *)sound_buf;
+    *start = sound_buf;
     *size = NBSAMPLES*sizeof(sound_buf[0]); 
 }
 
@@ -339,7 +339,7 @@ static void start_sound(void)
     wsg3_set_sampling_rate(rb->hw_freq_sampr[sr_index]);
 
     rb->pcm_set_frequency(rb->hw_freq_sampr[sr_index]);
-    rb->pcm_play_data(get_more, NULL, 0);
+    rb->pcm_play_data(get_more, NULL, NULL, 0);
 
     sound_playing = true;
 }
diff --git a/apps/plugins/pdbox/PDa/src/s_audio_rockbox.c b/apps/plugins/pdbox/PDa/src/s_audio_rockbox.c
index 76a50fa075..6571f74edf 100644
--- a/apps/plugins/pdbox/PDa/src/s_audio_rockbox.c
+++ b/apps/plugins/pdbox/PDa/src/s_audio_rockbox.c
@@ -26,7 +26,7 @@
 #include "s_stuff.h"
 
 /* Declare functions that go to IRAM. */
-void pdbox_get_more(unsigned char** start, size_t* size) ICODE_ATTR;
+void pdbox_get_more(const void** start, size_t* size) ICODE_ATTR;
 int rockbox_send_dacs(void) ICODE_ATTR;
 
 /* Extern variables. */
@@ -90,12 +90,12 @@ void rockbox_close_audio(void)
 }
 
 /* Rockbox audio callback. */
-void pdbox_get_more(unsigned char** start, size_t* size)
+void pdbox_get_more(const void** start, size_t* size)
 {
     if(outbuf_fill > 0)
     {
         /* Store output data address and size. */
-        *start = (unsigned char*) outbuf[outbuf_tail].data;
+        *start = outbuf[outbuf_tail].data;
         *size = sizeof(outbuf[outbuf_tail].data);
 
         /* Free this part of output buffer. */
@@ -116,8 +116,6 @@ void pdbox_get_more(unsigned char** start, size_t* size)
         playing = false;
 
         /* Nothing to play. */
-        *start = NULL;
-        *size = 0;
     }
 }
 
@@ -185,7 +183,7 @@ int rockbox_send_dacs(void)
     if(!playing && outbuf_fill > 0)
     {
         /* Start playing. */
-        rb->pcm_play_data(pdbox_get_more, NULL, 0);
+        rb->pcm_play_data(pdbox_get_more, NULL, NULL, 0);
 
         /* Set status flag. */
         playing = true;
diff --git a/apps/plugins/pitch_detector.c b/apps/plugins/pitch_detector.c
index c30d48a025..4ae43b3236 100644
--- a/apps/plugins/pitch_detector.c
+++ b/apps/plugins/pitch_detector.c
@@ -952,7 +952,7 @@ static uint32_t ICODE_ATTR buffer_magnitude(int16_t *input)
 }
 
 /* Stop the recording when the buffer is full */
-static void recording_callback(int status, void **start, size_t *size)
+static void recording_callback(void **start, size_t *size)
 {
     int tail = audio_tail ^ 1;
 
@@ -963,8 +963,6 @@ static void recording_callback(int status, void **start, size_t *size)
     /* Always record full buffer, even if not required */
     *start = audio_data[tail];
     *size = BUFFER_SIZE * sizeof (int16_t);
-
-    (void)status;
 }
 #endif /* SIMULATOR */
 
@@ -973,7 +971,8 @@ static void record_data(void)
 {
 #ifndef SIMULATOR
     /* Always record full buffer, even if not required */
-    rb->pcm_record_data(recording_callback, audio_data[audio_tail],
+    rb->pcm_record_data(recording_callback, NULL,
+                        audio_data[audio_tail],
                         BUFFER_SIZE * sizeof (int16_t));
 #endif
 }
diff --git a/apps/plugins/rockboy/rbsound.c b/apps/plugins/rockboy/rbsound.c
index c0d0277915..628879b4b7 100644
--- a/apps/plugins/rockboy/rbsound.c
+++ b/apps/plugins/rockboy/rbsound.c
@@ -16,10 +16,10 @@ static unsigned short *buf=0, *hwbuf=0;
 
 static bool newly_started;
 
-static void get_more(unsigned char** start, size_t* size)
+static void get_more(const void** start, size_t* size)
 {
     memcpy(hwbuf, &buf[pcm.len*doneplay], BUF_SIZE*sizeof(short));
-    *start = (unsigned char*)(hwbuf);
+    *start = hwbuf;
     *size = BUF_SIZE*sizeof(short);
     doneplay=1;
 }
@@ -76,7 +76,7 @@ int rockboy_pcm_submit(void)
 
     if(newly_started)
     {
-        rb->pcm_play_data(&get_more,NULL,0);
+        rb->pcm_play_data(&get_more, NULL, NULL,0);
         newly_started = false;
     }
 
diff --git a/apps/plugins/test_sampr.c b/apps/plugins/test_sampr.c
index db8301bba6..fc2f695c70 100644
--- a/apps/plugins/test_sampr.c
+++ b/apps/plugins/test_sampr.c
@@ -90,13 +90,13 @@ static int16_t ICODE_ATTR fsin(uint32_t phase)
 }
 
 /* ISR handler to get next block of data */
-static void get_more(unsigned char **start, size_t *size)
+static void get_more(const void **start, size_t *size)
 {
     /* Free previous buffer */
     output_head += output_step;
     output_step = 0;
 
-    *start = (unsigned char *)output_buf[output_head & OUTPUT_CHUNK_MASK];
+    *start = output_buf[output_head & OUTPUT_CHUNK_MASK];
     *size  = OUTPUT_CHUNK_SIZE;
 
     /* Keep repeating previous if source runs low */
@@ -236,7 +236,7 @@ static void play_tone(bool volume_set)
                                       IF_PRIO(, PRIORITY_PLAYBACK)
                                       IF_COP(, CPU));
 
-    rb->pcm_play_data(get_more, NULL, 0);
+    rb->pcm_play_data(get_more, NULL, NULL, 0);
 
 #ifndef HAVE_VOLUME_IN_LIST
     if (volume_set)
diff --git a/apps/plugins/zxbox/spsound.c b/apps/plugins/zxbox/spsound.c
index 8b3aa3d84f..9d3eefa87f 100644
--- a/apps/plugins/zxbox/spsound.c
+++ b/apps/plugins/zxbox/spsound.c
@@ -189,12 +189,11 @@ void autoclose_sound(void)
   }
 #endif
 }
-static void get_more(unsigned char** start, size_t* size)
+static void get_more(const void** start, size_t* size)
 {
     doneplay = 1;
-    rb->pcm_play_stop();
-   (void)*start;
-   (void)*size;
+    (void)start;
+    (void)size;
 }
 
 /* sp_sound_buf is Unsigned 8 bit, Rate 8000 Hz, Mono */
@@ -219,7 +218,7 @@ static void write_buf(void){
                     = my_buf[j+10] = my_buf[j+11] \
                     = (((byte)sp_sound_buf[i])<<8) >> settings.volume;
 
-    rb->pcm_play_data(&get_more,(unsigned char*)(my_buf),TMNUM*4*3*2);
+    rb->pcm_play_data(&get_more,NULL,(unsigned char*)(my_buf),TMNUM*4*3*2);
 
 #if 0
     /* can use to save and later analyze what we produce */
diff --git a/apps/recorder/pcm_record.c b/apps/recorder/pcm_record.c
index 90a6163b8f..d904be9a4e 100644
--- a/apps/recorder/pcm_record.c
+++ b/apps/recorder/pcm_record.c
@@ -257,20 +257,9 @@ enum
 /*******************************************************************/
     
 /* Callback for when more data is ready - called in interrupt context */
-static void pcm_rec_have_more(int status, void **start, size_t *size)
+static void pcm_rec_have_more(void **start, size_t *size)
 {
-    if (status < 0)
-    {
-        /* some error condition */
-        if (status == DMA_REC_ERROR_DMA)
-        {
-            /* Flush recorded data to disk and stop recording */
-            queue_post(&pcmrec_queue, PCMREC_STOP, 0);
-            return;
-        }
-        /* else try again next transmission - frame is invalid */
-    }
-    else if (!dma_lock)
+    if (!dma_lock)
     {
         /* advance write position */
         int next_pos = (dma_wr_pos + PCM_CHUNK_SIZE) & PCM_CHUNK_MASK;
@@ -287,6 +276,23 @@ static void pcm_rec_have_more(int status, void **start, size_t *size)
     *size = PCM_CHUNK_SIZE;
 } /* pcm_rec_have_more */
 
+static enum pcm_dma_status pcm_rec_status_callback(enum pcm_dma_status status)
+{
+    if (status < PCM_DMAST_OK)
+    {
+        /* some error condition */
+        if (status == PCM_DMAST_ERR_DMA)
+        {
+            /* Flush recorded data to disk and stop recording */
+            queue_post(&pcmrec_queue, PCMREC_STOP, 0);
+            return status;
+        }
+        /* else try again next transmission - frame is invalid */
+    }
+
+    return PCM_DMAST_OK;
+} /* pcm_rec_status_callback */
+
 static void reset_hardware(void)
 {
     /* reset pcm to defaults */
@@ -1239,8 +1245,8 @@ static void pcmrec_set_recording_options(
     {
         /* start DMA transfer */
         dma_lock = pre_record_ticks == 0;
-        pcm_record_data(pcm_rec_have_more, GET_PCM_CHUNK(dma_wr_pos),
-                        PCM_CHUNK_SIZE);
+        pcm_record_data(pcm_rec_have_more, pcm_rec_status_callback,
+                        GET_PCM_CHUNK(dma_wr_pos), PCM_CHUNK_SIZE);
     }
     else
     {
diff --git a/apps/voice_thread.c b/apps/voice_thread.c
index 2f216cde9d..5d23a74cbc 100644
--- a/apps/voice_thread.c
+++ b/apps/voice_thread.c
@@ -116,9 +116,12 @@ enum voice_thread_messages
 /* Structure to store clip data callback info */
 struct voice_info
 {
-    pcm_play_callback_type get_more; /* Callback to get more clips */
-    unsigned char *start;            /* Start of clip */
-    size_t size;                     /* Size of clip */
+    /* Callback to get more clips */
+    void (*get_more)(unsigned char** start, size_t* size);
+    /* Start of clip */
+    unsigned char *start;
+    /* Size of clip */
+    size_t size;
 };
 
 /* Private thread data for its current state that must be passed to its
@@ -148,14 +151,14 @@ static inline int voice_unplayed_frames(void)
 }
 
 /* Mixer channel callback */
-static void voice_pcm_callback(unsigned char **start, size_t *size)
+static void voice_pcm_callback(const void **start, size_t *size)
 {
     if (voice_unplayed_frames() == 0)
         return; /* Done! */
 
     unsigned int i = ++cur_buf_out % VOICE_FRAMES;
 
-    *start = (unsigned char *)voicebuf[i];
+    *start = voicebuf[i];
     *size = voicebuf_sizes[i];
 }
 
@@ -167,7 +170,7 @@ static void voice_start_playback(void)
 
     unsigned int i = cur_buf_out % VOICE_FRAMES;
     mixer_channel_play_data(PCM_MIXER_CHAN_VOICE, voice_pcm_callback,
-                            (unsigned char *)voicebuf[i], voicebuf_sizes[i]);
+                            voicebuf[i], voicebuf_sizes[i]);
 }
 
 /* Stop the voice channel */
@@ -198,7 +201,7 @@ static void voice_buf_commit(size_t size)
 
 /* Stop any current clip and start playing a new one */
 void mp3_play_data(const unsigned char* start, int size,
-                   pcm_play_callback_type get_more)
+                   void (*get_more)(unsigned char** start, size_t* size))
 {
     if (get_more != NULL && start != NULL && (ssize_t)size > 0)
     {
diff --git a/firmware/asm/arm/pcm-mixer-armv4.c b/firmware/asm/arm/pcm-mixer-armv4.c
index 4818544d7b..dc2edb781c 100644
--- a/firmware/asm/arm/pcm-mixer-armv4.c
+++ b/firmware/asm/arm/pcm-mixer-armv4.c
@@ -24,9 +24,9 @@
 
 /* Mix channels' samples and apply gain factors */
 static FORCE_INLINE void mix_samples(void *out,
-                                     void *src0,
+                                     const void *src0,
                                      int32_t src0_amp,
-                                     void *src1,
+                                     const void *src1,
                                      int32_t src1_amp,
                                      size_t size)
 {
@@ -96,7 +96,7 @@ static FORCE_INLINE void mix_samples(void *out,
         if (src0_amp != MIX_AMP_UNITY)
         {
             /* Keep unity in src0, amp0 */
-            int16_t *src_tmp = src0;
+            const void *src_tmp = src0;
             src0 = src1;
             src1 = src_tmp;
             src1_amp = src0_amp;
@@ -133,7 +133,7 @@ static FORCE_INLINE void mix_samples(void *out,
 
 /* Write channel's samples and apply gain factor */
 static FORCE_INLINE void write_samples(void *out,
-                                       void *src,
+                                       const void *src,
                                        int32_t amp,
                                        size_t size)
 {
diff --git a/firmware/asm/arm/pcm-mixer-armv5.c b/firmware/asm/arm/pcm-mixer-armv5.c
index 64f2c86f52..add1522fd9 100644
--- a/firmware/asm/arm/pcm-mixer-armv5.c
+++ b/firmware/asm/arm/pcm-mixer-armv5.c
@@ -24,9 +24,9 @@
 
 /* Mix channels' samples and apply gain factors */
 static FORCE_INLINE void mix_samples(void *out,
-                                     void *src0,
+                                     const void *src0,
                                      int32_t src0_amp,
-                                     void *src1,
+                                     const void *src1,
                                      int32_t src1_amp,
                                      size_t size)
 {
@@ -57,7 +57,7 @@ static FORCE_INLINE void mix_samples(void *out,
 
 /* Write channel's samples and apply gain factor */
 static FORCE_INLINE void write_samples(void *out,
-                                       void *src,
+                                       const void *src,
                                        int32_t amp,
                                        size_t size)
 {
diff --git a/firmware/asm/arm/pcm-mixer-armv6.c b/firmware/asm/arm/pcm-mixer-armv6.c
index 94eecd0f90..9da5b40ef1 100644
--- a/firmware/asm/arm/pcm-mixer-armv6.c
+++ b/firmware/asm/arm/pcm-mixer-armv6.c
@@ -23,9 +23,9 @@
 
 /* Mix channels' samples and apply gain factors */
 static FORCE_INLINE void mix_samples(void *out,
-                                     void *src0,
+                                     const void *src0,
                                      int32_t src0_amp,
-                                     void *src1,
+                                     const void *src1,
                                      int32_t src1_amp,
                                      size_t size)
 {
@@ -71,7 +71,7 @@ static FORCE_INLINE void mix_samples(void *out,
 
 /* Write channel's samples and apply gain factor */
 static FORCE_INLINE void write_samples(void *out,
-                                       void *src,
+                                       const void *src,
                                        int32_t amp,
                                        size_t size)
 {
diff --git a/firmware/asm/m68k/pcm-mixer.c b/firmware/asm/m68k/pcm-mixer.c
index d8318fffaf..730ae4ace7 100644
--- a/firmware/asm/m68k/pcm-mixer.c
+++ b/firmware/asm/m68k/pcm-mixer.c
@@ -56,9 +56,9 @@ static FORCE_INLINE void restore_emac_context(void)
 
 /* Mix channels' samples and apply gain factors */
 static FORCE_INLINE void mix_samples(void *out,
-                                     void *src0,
+                                     const void *src0,
                                      int32_t src0_amp,
-                                     void *src1,
+                                     const void *src1,
                                      int32_t src1_amp,
                                      size_t size)
 {
@@ -94,7 +94,7 @@ static FORCE_INLINE void mix_samples(void *out,
 
 /* Write channel's samples and apply gain factor */
 static FORCE_INLINE void write_samples(void *out,
-                                       void *src,
+                                       const void *src,
                                        int32_t amp,
                                        size_t size)
 {
diff --git a/firmware/asm/pcm-mixer.c b/firmware/asm/pcm-mixer.c
index 62dfa3e9db..3e6e2fff78 100644
--- a/firmware/asm/pcm-mixer.c
+++ b/firmware/asm/pcm-mixer.c
@@ -28,9 +28,9 @@
 #include "dsp-util.h" /* for clip_sample_16 */
 /* Mix channels' samples and apply gain factors */
 static FORCE_INLINE void mix_samples(int16_t *out,
-                                     int16_t *src0,
+                                     const int16_t *src0,
                                      int32_t src0_amp,
-                                     int16_t *src1,
+                                     const int16_t *src1,
                                      int32_t src1_amp,
                                      size_t size)
 {
@@ -64,7 +64,7 @@ static FORCE_INLINE void mix_samples(int16_t *out,
         if (src0_amp != MIX_AMP_UNITY)
         {
             /* Keep unity in src0, amp0 */
-            int16_t *src_tmp = src0;
+            const int16_t *src_tmp = src0;
             src0 = src1;
             src1 = src_tmp;
             src1_amp = src0_amp;
@@ -84,7 +84,7 @@ static FORCE_INLINE void mix_samples(int16_t *out,
 
 /* Write channel's samples and apply gain factor */
 static FORCE_INLINE void write_samples(int16_t *out,
-                                       int16_t *src,
+                                       const int16_t *src,
                                        int32_t amp,
                                        size_t size)
 {
diff --git a/firmware/export/pcm-internal.h b/firmware/export/pcm-internal.h
index 89d895fe4b..abe3fe08dc 100644
--- a/firmware/export/pcm-internal.h
+++ b/firmware/export/pcm-internal.h
@@ -41,24 +41,28 @@ void pcm_do_peak_calculation(struct pcm_peaks *peaks, bool active,
 
 /** The following are for internal use between pcm.c and target-
     specific portion **/
+static FORCE_INLINE enum pcm_dma_status pcm_call_status_cb(
+    pcm_status_callback_type callback, enum pcm_dma_status status)
+{
+    if (!callback)
+        return status;
 
-/* Called by the bottom layer ISR when more data is needed. Returns non-
- * zero size if more data is to be played. Setting start to NULL
- * forces stop. */
-void pcm_play_get_more_callback(void **start, size_t *size);
+    return callback(status);
+}
 
-/* Called by the bottom layer ISR after next transfer has begun in order
-   to fill more data for next "get more" callback to implement double-buffered
-   callbacks - except for a couple ASM handlers, help drivers to implement
-   this functionality with minimal overhead */
-static FORCE_INLINE void pcm_play_dma_started_callback(void)
+static FORCE_INLINE enum pcm_dma_status
+pcm_play_dma_status_callback(enum pcm_dma_status status)
 {
-    extern void (* pcm_play_dma_started)(void);
-    void (* callback)(void) = pcm_play_dma_started;
-    if (callback)
-        callback();
+    extern enum pcm_dma_status
+        (* volatile pcm_play_status_callback)(enum pcm_dma_status);
+    return pcm_call_status_cb(pcm_play_status_callback, status);
 }
 
+/* Called by the bottom layer ISR when more data is needed. Returns true
+ * if a new buffer is available, false otherwise. */
+bool pcm_play_dma_complete_callback(enum pcm_dma_status status,
+                                    const void **addr, size_t *size);
+
 extern unsigned long pcm_curr_sampr;
 extern unsigned long pcm_sampr;
 extern int pcm_fsel;
@@ -90,10 +94,29 @@ extern volatile bool pcm_recording;
 void pcm_rec_dma_init(void);
 void pcm_rec_dma_close(void);
 void pcm_rec_dma_start(void *addr, size_t size);
-void pcm_rec_dma_record_more(void *start, size_t size);
 void pcm_rec_dma_stop(void);
 const void * pcm_rec_dma_get_peak_buffer(void);
 
+static FORCE_INLINE enum pcm_dma_status
+pcm_rec_dma_status_callback(enum pcm_dma_status status)
+{
+    extern enum pcm_dma_status
+        (* volatile pcm_rec_status_callback)(enum pcm_dma_status);
+    return pcm_call_status_cb(pcm_rec_status_callback, status);
+}
+
+
+/* Called by the bottom layer ISR when more data is needed. Returns true
+ * if a new buffer is available, false otherwise. */
+bool pcm_rec_dma_complete_callback(enum pcm_dma_status status,
+                                   void **addr, size_t *size);
+
+#ifdef HAVE_PCM_REC_DMA_ADDRESS
+#define pcm_rec_dma_addr(addr) pcm_dma_addr(addr)
+#else
+#define pcm_rec_dma_addr(addr) addr
+#endif
+
 #endif /* HAVE_RECORDING */
 
 #endif /* PCM_INTERNAL_H */
diff --git a/firmware/export/pcm.h b/firmware/export/pcm.h
index 4a7a5b3193..df82c6092d 100644
--- a/firmware/export/pcm.h
+++ b/firmware/export/pcm.h
@@ -24,17 +24,23 @@
 #include <string.h> /* size_t */
 #include "config.h"
 
-#define DMA_REC_ERROR_DMA       (-1)
+enum pcm_dma_status
+{
 #ifdef HAVE_SPDIF_REC
-#define DMA_REC_ERROR_SPDIF     (-2)
+    PCM_DMAST_ERR_SPDIF = -2,
 #endif
+    PCM_DMAST_ERR_DMA   = -1,
+    PCM_DMAST_OK        =  0,
+    PCM_DMAST_STARTED   =  1,
+};
 
 /** RAW PCM routines used with playback and recording **/
 
-/* Typedef for registered callbacks */
-typedef void (*pcm_play_callback_type)(unsigned char **start,
-                                       size_t *size);
-typedef void (*pcm_rec_callback_type)(int status, void **start, size_t *size);
+/* Typedef for registered data callback */
+typedef void (*pcm_play_callback_type)(const void **start, size_t *size);
+
+/* Typedef for registered status callback */
+typedef enum pcm_dma_status (*pcm_status_callback_type)(enum pcm_dma_status status);
 
 /* set the pcm frequency - use values in hw_sampr_list 
  * when CONFIG_SAMPR_TYPES is #defined, or-in SAMPR_TYPE_* fields with
@@ -62,7 +68,8 @@ bool pcm_is_initialized(void);
 
 /* This is for playing "raw" PCM data */
 void pcm_play_data(pcm_play_callback_type get_more,
-                   unsigned char* start, size_t size);
+                   pcm_status_callback_type status_cb,
+                   const void *start, size_t size);
 
 void pcm_calculate_peaks(int *left, int *right);
 const void* pcm_get_peak_buffer(int* count);
@@ -73,12 +80,13 @@ void pcm_play_pause(bool play);
 bool pcm_is_paused(void);
 bool pcm_is_playing(void);
 
-void pcm_play_set_dma_started_callback(void (* callback)(void));
-
 #ifdef HAVE_RECORDING
 
 /** RAW PCM recording routines **/
 
+/* Typedef for registered data callback */
+typedef void (*pcm_rec_callback_type)(void **start, size_t *size);
+
 /* Reenterable locks for locking and unlocking the recording interrupt */
 void pcm_rec_lock(void);
 void pcm_rec_unlock(void);
@@ -90,6 +98,7 @@ void pcm_close_recording(void);
 
 /* Start recording "raw" PCM data */
 void pcm_record_data(pcm_rec_callback_type more_ready,
+                     pcm_status_callback_type status_cb,
                      void *start, size_t size);
 
 /* Stop tranferring data into supplied buffer */
@@ -98,10 +107,6 @@ void pcm_stop_recording(void);
 /* Is pcm currently recording? */
 bool pcm_is_recording(void);
 
-/* Called by bottom layer ISR when transfer is complete. Returns non-zero
- * size if successful. Setting start to NULL forces stop. */
-void pcm_rec_more_ready_callback(int status, void **start, size_t *size);
-
 void pcm_calculate_rec_peaks(int *left, int *right);
 
 #endif /* HAVE_RECORDING */
diff --git a/firmware/export/pcm_mixer.h b/firmware/export/pcm_mixer.h
index ea26060452..6e1632d5ae 100644
--- a/firmware/export/pcm_mixer.h
+++ b/firmware/export/pcm_mixer.h
@@ -86,7 +86,7 @@ enum channel_status
 /* Start playback on a channel */
 void mixer_channel_play_data(enum pcm_mixer_channel channel,
                              pcm_play_callback_type get_more,
-                             unsigned char *start, size_t size);
+                             const void *start, size_t size);
 
 /* Pause or resume a channel (when started) */
 void mixer_channel_play_pause(enum pcm_mixer_channel channel, bool play);
@@ -105,7 +105,7 @@ enum channel_status mixer_channel_status(enum pcm_mixer_channel channel);
 size_t mixer_channel_get_bytes_waiting(enum pcm_mixer_channel channel);
 
 /* Return pointer to channel's playing audio data and the size remaining */
-void * mixer_channel_get_buffer(enum pcm_mixer_channel channel, int *count);
+const void * mixer_channel_get_buffer(enum pcm_mixer_channel channel, int *count);
 
 /* Calculate peak values for channel */
 void mixer_channel_calculate_peaks(enum pcm_mixer_channel channel,
diff --git a/firmware/export/pp5002.h b/firmware/export/pp5002.h
index 95cc8d5058..5966f10d08 100644
--- a/firmware/export/pp5002.h
+++ b/firmware/export/pp5002.h
@@ -43,7 +43,9 @@
 #define IISCONFIG        (*(volatile unsigned long *)(0xc0002500))
 #define IISFIFO_CFG      (*(volatile unsigned long *)(0xc000251c))
 #define IISFIFO_WR       (*(volatile unsigned long *)(0xc0002540))
+#define IISFIFO_WRH      (*(volatile unsigned short *)(0xc0002540))
 #define IISFIFO_RD       (*(volatile unsigned long *)(0xc0002580))
+#define IISFIFO_RDH      (*(volatile unsigned short *)(0xc0002540))
 
 /**
  * IISCONFIG bits:
diff --git a/firmware/pcm.c b/firmware/pcm.c
index d1a897dcab..621ed56e0d 100644
--- a/firmware/pcm.c
+++ b/firmware/pcm.c
@@ -41,7 +41,8 @@
  *      pcm_play_lock
  *      pcm_play_unlock
  *   Semi-private -
- *      pcm_play_get_more_callback
+ *      pcm_play_dma_complete_callback
+ *      pcm_play_dma_status_callback
  *      pcm_play_dma_init
  *      pcm_play_dma_postinit
  *      pcm_play_dma_start
@@ -66,7 +67,8 @@
  *      pcm_rec_lock
  *      pcm_rec_unlock
  *   Semi-private -
- *      pcm_rec_more_ready_callback
+ *      pcm_rec_dma_complete_callback
+ *      pcm_rec_dma_status_callback
  *      pcm_rec_dma_init
  *      pcm_rec_dma_close
  *      pcm_rec_dma_start
@@ -83,9 +85,12 @@
 /* 'true' when all stages of pcm initialization have completed */
 static bool pcm_is_ready = false;
 
-/* the registered callback function to ask for more mp3 data */
-static pcm_play_callback_type pcm_callback_for_more SHAREDBSS_ATTR = NULL;
-void (* pcm_play_dma_started)(void) SHAREDBSS_ATTR = NULL;
+/* The registered callback function to ask for more mp3 data */
+static volatile pcm_play_callback_type
+    pcm_callback_for_more SHAREDBSS_ATTR = NULL;
+/* The registered callback function to inform of DMA status */
+volatile pcm_status_callback_type
+    pcm_play_status_callback SHAREDBSS_ATTR = NULL;
 /* PCM playback state */
 volatile bool pcm_playing SHAREDBSS_ATTR = false;
 /* PCM paused state. paused implies playing */
@@ -104,7 +109,7 @@ static struct pcm_peaks global_peaks;
 static void pcm_play_stopped(void)
 {
     pcm_callback_for_more = NULL;
-    pcm_play_dma_started = NULL;
+    pcm_play_status_callback = NULL;
     pcm_paused = false;
     pcm_playing = false;
 }
@@ -258,27 +263,29 @@ bool pcm_is_initialized(void)
 }
 
 /* Common code to pcm_play_data and pcm_play_pause */
-static void pcm_play_data_start(unsigned char *start, size_t size)
+static void pcm_play_data_start(const void *addr, size_t size)
 {
-    ALIGN_AUDIOBUF(start, size);
+    ALIGN_AUDIOBUF(addr, size);
 
-    if (!(start && size))
+    if (!(addr && size))
     {
         pcm_play_callback_type get_more = pcm_callback_for_more;
+        addr = NULL;
         size = 0;
+
         if (get_more)
         {
             logf(" get_more");
-            get_more(&start, &size);
-            ALIGN_AUDIOBUF(start, size);
+            get_more(&addr, &size);
+            ALIGN_AUDIOBUF(addr, size);
         }
     }
 
-    if (start && size)
+    if (addr && size)
     {
         logf(" pcm_play_dma_start");
         pcm_apply_settings();
-        pcm_play_dma_start(start, size);
+        pcm_play_dma_start(addr, size);
         pcm_playing = true;
         pcm_paused = false;
         return;
@@ -291,13 +298,15 @@ static void pcm_play_data_start(unsigned char *start, size_t size)
 }
 
 void pcm_play_data(pcm_play_callback_type get_more,
-                   unsigned char *start, size_t size)
+                   pcm_status_callback_type status_cb,
+                   const void *start, size_t size)
 {
     logf("pcm_play_data");
 
     pcm_play_lock();
 
     pcm_callback_for_more = get_more;
+    pcm_play_status_callback = status_cb;
 
     logf(" pcm_play_data_start");
     pcm_play_data_start(start, size);
@@ -305,26 +314,33 @@ void pcm_play_data(pcm_play_callback_type get_more,
     pcm_play_unlock();
 }
 
-void pcm_play_get_more_callback(void **start, size_t *size)
+bool pcm_play_dma_complete_callback(enum pcm_dma_status status,
+                                    const void **addr, size_t *size)
 {
-    pcm_play_callback_type get_more = pcm_callback_for_more;
+    /* Check status callback first if error */
+    if (status < PCM_DMAST_OK)
+        status = pcm_play_dma_status_callback(status);
 
-    *size = 0;
+    pcm_play_callback_type get_more = pcm_callback_for_more;
 
-    if (get_more && start)
+    if (get_more && status >= PCM_DMAST_OK)
     {
-        /* Call registered callback */
-        get_more((unsigned char **)start, size);
+        *addr = NULL;
+        *size = 0;
 
-        ALIGN_AUDIOBUF(*start, *size);
+        /* Call registered callback to obtain next buffer */
+        get_more(addr, size);
+        ALIGN_AUDIOBUF(*addr, *size);
 
-        if (*start && *size)
-            return;
+        if (*addr && *size)
+            return true;
     } 
 
     /* Error, callback missing or no more DMA to do */
     pcm_play_dma_stop();
     pcm_play_stopped();
+
+    return false;
 }
 
 void pcm_play_pause(bool play)
@@ -428,12 +444,6 @@ void pcm_apply_settings(void)
     }
 }
 
-/* register callback to buffer more data */
-void pcm_play_set_dma_started_callback(void (* callback)(void))
-{
-    pcm_play_dma_started = callback;
-}
-
 #ifdef HAVE_RECORDING
 /** Low level pcm recording apis **/
 
@@ -442,6 +452,8 @@ static const void * volatile pcm_rec_peak_addr SHAREDBSS_ATTR = NULL;
 /* the registered callback function for when more data is available */
 static volatile pcm_rec_callback_type
     pcm_callback_more_ready SHAREDBSS_ATTR = NULL;
+volatile pcm_status_callback_type
+    pcm_rec_status_callback SHAREDBSS_ATTR = NULL;
 /* DMA transfer in is currently active */
 volatile bool pcm_recording SHAREDBSS_ATTR = false;
 
@@ -450,6 +462,7 @@ static void pcm_recording_stopped(void)
 {
     pcm_recording = false;
     pcm_callback_more_ready = NULL;
+    pcm_rec_status_callback = NULL;
 }
 
 /**
@@ -542,13 +555,14 @@ void pcm_close_recording(void)
 }
 
 void pcm_record_data(pcm_rec_callback_type more_ready,
-                     void *start, size_t size)
+                     pcm_status_callback_type status_cb,
+                     void *addr, size_t size)
 {
     logf("pcm_record_data");
 
-    ALIGN_AUDIOBUF(start, size);
+    ALIGN_AUDIOBUF(addr, size);
 
-    if (!(start && size))
+    if (!(addr && size))
     {
         logf(" no buffer");
         return;
@@ -557,17 +571,14 @@ void pcm_record_data(pcm_rec_callback_type more_ready,
     pcm_rec_lock();
 
     pcm_callback_more_ready = more_ready;
+    pcm_rec_status_callback = status_cb;
 
-#ifdef HAVE_PCM_REC_DMA_ADDRESS
     /* Need a physical DMA address translation, if not already physical. */
-    pcm_rec_peak_addr = pcm_dma_addr(start);
-#else
-    pcm_rec_peak_addr = start;
-#endif
+    pcm_rec_peak_addr = pcm_rec_dma_addr(addr);
 
     logf(" pcm_rec_dma_start");
     pcm_apply_settings();
-    pcm_rec_dma_start(start, size);
+    pcm_rec_dma_start(addr, size);
     pcm_recording = true;
 
     pcm_rec_unlock();
@@ -589,33 +600,35 @@ void pcm_stop_recording(void)
     pcm_rec_unlock();
 } /* pcm_stop_recording */
 
-void pcm_rec_more_ready_callback(int status, void **start, size_t *size)
+bool pcm_rec_dma_complete_callback(enum pcm_dma_status status,
+                                   void **addr, size_t *size)
 {
-    pcm_rec_callback_type have_more = pcm_callback_more_ready;
+     /* Check status callback first if error */
+    if (status < PCM_DMAST_OK)
+        status = pcm_rec_dma_status_callback(status);
 
-    *size = 0;
+    pcm_rec_callback_type have_more = pcm_callback_more_ready;
 
-    if (have_more && start)
+    if (have_more && status >= PCM_DMAST_OK)
     {
-        have_more(status, start, size);
-        ALIGN_AUDIOBUF(*start, *size);
+        /* Call registered callback to obtain next buffer */
+        have_more(addr, size);
+        ALIGN_AUDIOBUF(*addr, *size);
 
-        if (*start && *size)
+        if (*addr && *size)
         {
-        #ifdef HAVE_PCM_REC_DMA_ADDRESS
             /* Need a physical DMA address translation, if not already
              * physical. */
-            pcm_rec_peak_addr = pcm_dma_addr(*start);
-        #else
-            pcm_rec_peak_addr = *start;
-        #endif
-            return;
+            pcm_rec_peak_addr = pcm_rec_dma_addr(*addr);
+            return true;
         }
     }
 
     /* Error, callback missing or no more DMA to do */
     pcm_rec_dma_stop();
     pcm_recording_stopped();
+
+    return false;
 }
 
 #endif /* HAVE_RECORDING */
diff --git a/firmware/pcm_mixer.c b/firmware/pcm_mixer.c
index 4fd96bc97c..9077c6f271 100644
--- a/firmware/pcm_mixer.c
+++ b/firmware/pcm_mixer.c
@@ -39,7 +39,7 @@
 /* Descriptor for each channel */
 struct mixer_channel
 {
-    unsigned char *start;            /* Buffer pointer */
+    const void *start;               /* Buffer pointer */
     size_t size;                     /* Bytes remaining */
     size_t last_size;                /* Size of consumed data in prev. cycle */
     pcm_play_callback_type get_more; /* Registered callback */
@@ -103,16 +103,20 @@ static void channel_stopped(struct mixer_channel *chan)
 }
 
 /* Main PCM callback - sends the current prepared frame to play */
-static void mixer_pcm_callback(unsigned char **start, size_t *size)
+static void mixer_pcm_callback(const void **addr, size_t *size)
 {
-    *start = (unsigned char *)downmix_buf[downmix_index];
+    *addr = downmix_buf[downmix_index];
     *size = next_size;
 }
 
 /* Buffering callback - calls sub-callbacks and mixes the data for next
    buffer to be sent from mixer_pcm_callback() */
-static void MIXER_CALLBACK_ICODE mixer_buffer_callback(void)
+static enum pcm_dma_status MIXER_CALLBACK_ICODE
+mixer_buffer_callback(enum pcm_dma_status status)
 {
+    if (status != PCM_DMAST_STARTED)
+        return status;
+
     downmix_index ^= 1; /* Next buffer */
 
     void *mixptr = downmix_buf[downmix_index];
@@ -169,12 +173,11 @@ fill_frame:
 
         if (LIKELY(!*chan_p))
         {
-            write_samples(mixptr, (void *)chan->start,
-                          chan->amplitude, mixsize);
+            write_samples(mixptr, chan->start, chan->amplitude, mixsize);
         }
         else
         {
-            void *src0, *src1;
+            const void *src0, *src1;
             unsigned int amp0, amp1;
 
             /* Mix first two channels with each other as the downmix */
@@ -228,6 +231,8 @@ fill_frame:
     if (next_size)
         *downmix_buf[downmix_index] = downmix_index ? 0x7fff7fff : 0x80008000;
 #endif
+
+    return PCM_DMAST_OK;
 }
 
 /* Start PCM driver if it's not currently playing */
@@ -245,15 +250,15 @@ static void mixer_start_pcm(void)
     pcm_set_frequency(NATIVE_FREQUENCY);
 
     /* Prepare initial frames and set up the double buffer */
-    mixer_buffer_callback();
+    mixer_buffer_callback(PCM_DMAST_STARTED);
 
     /* Save the previous call's output */
     void *start = downmix_buf[downmix_index];
 
-    mixer_buffer_callback();
+    mixer_buffer_callback(PCM_DMAST_STARTED);
 
-    pcm_play_set_dma_started_callback(mixer_buffer_callback);
-    pcm_play_data(mixer_pcm_callback, start, MIX_FRAME_SIZE);
+    pcm_play_data(mixer_pcm_callback, mixer_buffer_callback,
+                  start, MIX_FRAME_SIZE);
 }
 
 /** Public interfaces **/
@@ -261,7 +266,7 @@ static void mixer_start_pcm(void)
 /* Start playback on a channel */
 void mixer_channel_play_data(enum pcm_mixer_channel channel,
                              pcm_play_callback_type get_more,
-                             unsigned char *start, size_t size)
+                             const void *start, size_t size)
 {
     struct mixer_channel *chan = &channels[channel];
 
@@ -360,12 +365,12 @@ size_t mixer_channel_get_bytes_waiting(enum pcm_mixer_channel channel)
 }
 
 /* Return pointer to channel's playing audio data and the size remaining */
-void * mixer_channel_get_buffer(enum pcm_mixer_channel channel, int *count)
+const void * mixer_channel_get_buffer(enum pcm_mixer_channel channel, int *count)
 {
     struct mixer_channel *chan = &channels[channel];
-    void * buf = *(unsigned char * volatile *)&chan->start;
+    const void * buf = *(const void * volatile *)&chan->start;
     size_t size = *(size_t volatile *)&chan->size;
-    void * buf2 = *(unsigned char * volatile *)&chan->start;
+    const void * buf2 = *(const void * volatile *)&chan->start;
 
     /* Still same buffer? */
     if (buf == buf2)
diff --git a/firmware/target/arm/as3525/pcm-as3525.c b/firmware/target/arm/as3525/pcm-as3525.c
index 0ecc63d018..eb22fc2016 100644
--- a/firmware/target/arm/as3525/pcm-as3525.c
+++ b/firmware/target/arm/as3525/pcm-as3525.c
@@ -36,9 +36,9 @@
                                       * and the number of 32bits words has to
                                       * fit in 11 bits of DMA register */
 
-static void *dma_start_addr;    /* Pointer to callback buffer */
+static const void *dma_start_addr;    /* Pointer to callback buffer */
 static size_t dma_start_size;   /* Size of callback buffer */
-static void *dma_sub_addr;      /* Pointer to sub buffer */
+static const void *dma_sub_addr;      /* Pointer to sub buffer */
 static size_t dma_rem_size;     /* Remaining size - in 4*32 bits */
 static size_t play_sub_size;    /* size of current subtransfer */
 static void dma_callback(void);
@@ -100,9 +100,8 @@ static void dma_callback(void)
 
     if(!dma_rem_size)
     {
-        pcm_play_get_more_callback(&dma_start_addr, &dma_start_size);
-
-        if (!dma_start_size)
+        if(!pcm_play_dma_complete_callback(PCM_DMAST_OK, &dma_start_addr,
+                                           &dma_start_size))
             return;
 
         dma_sub_addr = dma_start_addr;
@@ -111,7 +110,7 @@ static void dma_callback(void)
         /* force writeback */
         commit_dcache_range(dma_start_addr, dma_start_size);
         play_start_pcm();
-        pcm_play_dma_started_callback();
+        pcm_play_dma_status_callback(PCM_DMAST_STARTED);
     }
     else
     {
@@ -123,7 +122,7 @@ void pcm_play_dma_start(const void *addr, size_t size)
 {
     is_playing = true;
 
-    dma_start_addr = (void*)addr;
+    dma_start_addr = addr;
     dma_start_size = size;
     dma_sub_addr = dma_start_addr;
     dma_rem_size = size;
@@ -368,7 +367,12 @@ void INT_I2SIN(void)
         }
     }
 
-    pcm_rec_more_ready_callback(0, (void *)&rec_dma_addr, &rec_dma_size);
+    /* Inform middle layer */
+    if (pcm_rec_dma_complete_callback(PCM_DMAST_OK, (void **)&rec_dma_addr,
+                                      &rec_dma_size))
+    {
+        pcm_rec_dma_status_callback(PCM_DMAST_STARTED);
+    }
 }
 
 
diff --git a/firmware/target/arm/imx233/pcm-imx233.c b/firmware/target/arm/imx233/pcm-imx233.c
index c8b79b3875..c4c512eed6 100644
--- a/firmware/target/arm/imx233/pcm-imx233.c
+++ b/firmware/target/arm/imx233/pcm-imx233.c
@@ -49,15 +49,13 @@ static void play(const void *addr, size_t size)
 
 void INT_DAC_DMA(void)
 {
-    void *start;
+    const void *start;
     size_t size;
 
-    pcm_play_get_more_callback(&start, &size);
-
-    if(size != 0)
+    if (pcm_play_dma_complete_callback(PCM_DMAST_OK, &start, &size))
     {
         play(start, size);
-        pcm_play_dma_started_callback();
+        pcm_play_dma_status_callback(PCM_DMAST_STARTED);
     }
 
     imx233_dma_clear_channel_interrupt(APB_AUDIO_DAC);
@@ -65,6 +63,7 @@ void INT_DAC_DMA(void)
 
 void INT_DAC_ERROR(void)
 {
+    /* TODO: Inform of error through pcm_play_dma_complete_callback */
 }
 
 void pcm_play_lock(void)
diff --git a/firmware/target/arm/imx31/gigabeat-s/pcm-gigabeat-s.c b/firmware/target/arm/imx31/gigabeat-s/pcm-gigabeat-s.c
index e106cf78e3..c26349b72e 100644
--- a/firmware/target/arm/imx31/gigabeat-s/pcm-gigabeat-s.c
+++ b/firmware/target/arm/imx31/gigabeat-s/pcm-gigabeat-s.c
@@ -78,12 +78,20 @@ static struct dma_data dma_play_data =
     .state = 0
 };
 
-static void play_dma_callback(void)
+static void play_start_dma(const void *addr, size_t size)
 {
-    void *start;
-    size_t size;
-    bool rror;
+    commit_dcache_range(addr, size);
+
+    dma_play_bd.buf_addr = (void *)addr_virt_to_phys((unsigned long)addr);
+    dma_play_bd.mode.count = size;
+    dma_play_bd.mode.command = TRANSFER_16BIT;
+    dma_play_bd.mode.status = BD_DONE | BD_WRAP | BD_INTR;
+
+    sdma_channel_run(DMA_PLAY_CH_NUM);
+}
 
+static void play_dma_callback(void)
+{
     if (dma_play_data.locked != 0)
     {
         /* Callback is locked out */
@@ -91,22 +99,17 @@ static void play_dma_callback(void)
         return;
     }
 
-    rror = dma_play_bd.mode.status & BD_RROR;
-
-    pcm_play_get_more_callback(rror ? NULL : &start, &size);
-
-    if (size == 0)
-        return;
-
-     /* Flush any pending cache writes */
-    commit_dcache_range(start, size);
-    dma_play_bd.buf_addr = (void *)addr_virt_to_phys((unsigned long)start);
-    dma_play_bd.mode.count = size;
-    dma_play_bd.mode.command = TRANSFER_16BIT;
-    dma_play_bd.mode.status = BD_DONE | BD_WRAP | BD_INTR;
-    sdma_channel_run(DMA_PLAY_CH_NUM);
-
-    pcm_play_dma_started_callback();
+    /* Inform of status and get new buffer */
+    enum pcm_dma_status status = (dma_play_bd.mode.status & BD_RROR) ?
+                  PCM_DMAST_ERR_DMA : PCM_DMAST_OK;
+    const void *addr;
+    size_t size;
+    
+    if (pcm_play_dma_complete_callback(status, &addr, &size))
+    {
+        play_start_dma(addr, size);
+        pcm_play_dma_status_callback(PCM_DMAST_STARTED);
+    }
 }
 
 void pcm_play_lock(void)
@@ -221,15 +224,11 @@ void pcm_play_dma_start(const void *addr, size_t size)
     if (!sdma_channel_reset(DMA_PLAY_CH_NUM))
         return;
 
-    commit_dcache_range(addr, size);
-    dma_play_bd.buf_addr =
-        (void *)addr_virt_to_phys((unsigned long)(void *)addr);
-    dma_play_bd.mode.count = size;
-    dma_play_bd.mode.command = TRANSFER_16BIT;
-    dma_play_bd.mode.status = BD_DONE | BD_WRAP | BD_INTR;
-
+    /* Begin I2S transmission */
     play_start_pcm();
-    sdma_channel_run(DMA_PLAY_CH_NUM);
+
+    /* Begin DMA transfer */
+    play_start_dma(addr, size);
 }
 
 void pcm_play_dma_stop(void)
@@ -332,37 +331,39 @@ static struct dma_data dma_rec_data =
     .state = 0
 };
 
-static void rec_dma_callback(void)
+static void rec_start_dma(void *addr, size_t size)
 {
-    int status = 0;
-    void *start;
-    size_t size;
+    discard_dcache_range(addr, size);
+
+    addr = (void *)addr_virt_to_phys((unsigned long)addr);
 
+    dma_rec_bd.buf_addr = addr;
+    dma_rec_bd.mode.count = size;
+    dma_rec_bd.mode.command = TRANSFER_16BIT;
+    dma_rec_bd.mode.status = BD_DONE | BD_WRAP | BD_INTR;
+
+    sdma_channel_run(DMA_REC_CH_NUM);
+}
+
+static void rec_dma_callback(void)
+{
     if (dma_rec_data.locked != 0)
     {
         dma_rec_data.callback_pending = dma_rec_data.state;
         return; /* Callback is locked out */
     }
 
-    if (dma_rec_bd.mode.status & BD_RROR)
-        status = DMA_REC_ERROR_DMA;
-
-    pcm_rec_more_ready_callback(status, &start, &size);
-
-    if (size == 0)
-        return;
-
-    /* Invalidate - buffer must be coherent */
-    discard_dcache_range(start, size);
-
-    start = (void *)addr_virt_to_phys((unsigned long)start);
-
-    dma_rec_bd.buf_addr = start;
-    dma_rec_bd.mode.count = size;
-    dma_rec_bd.mode.command = TRANSFER_16BIT;
-    dma_rec_bd.mode.status = BD_DONE | BD_WRAP | BD_INTR;
+    /* Inform middle layer */
+    enum pcm_dma_status status = (dma_rec_bd.mode.status & BD_RROR) ?
+                                  PCM_DMAST_ERR_DMA : PCM_DMAST_OK;
+    void *addr;
+    size_t size;
 
-    sdma_channel_run(DMA_REC_CH_NUM);
+    if (pcm_rec_dma_complete_callback(status, &addr, &size))
+    {
+        rec_start_dma(addr, size);
+        pcm_rec_dma_status_callback(PCM_DMAST_STARTED);
+    }
 }
 
 void pcm_rec_lock(void)
@@ -426,29 +427,21 @@ void pcm_rec_dma_start(void *addr, size_t size)
 
     if (!sdma_channel_reset(DMA_REC_CH_NUM))
         return;
-    
-    /* Invalidate - buffer must be coherent */
-    discard_dcache_range(addr, size);
 
-    addr = (void *)addr_virt_to_phys((unsigned long)addr);
-    dma_rec_bd.buf_addr = addr;
-    dma_rec_bd.mode.count = size;
-    dma_rec_bd.mode.command = TRANSFER_16BIT;
-    dma_rec_bd.mode.status = BD_DONE | BD_WRAP | BD_INTR;
+    /* Ensure clear FIFO */
+    while (SSI_SFCSR1 & SSI_SFCSR_RFCNT0)
+        SSI_SRX0_1;
 
     dma_rec_data.state = 1; /* Check callback on unlock */
 
     SSI_SRCR1 |= SSI_SRCR_RFEN0; /* Enable RX FIFO */
 
-    /* Ensure clear FIFO */
-    while (SSI_SFCSR1 & SSI_SFCSR_RFCNT0)
-        SSI_SRX0_1;
-
     /* Enable receive */
     SSI_SCR1 |= SSI_SCR_RE;
     SSI_SIER1 |= SSI_SIER_RDMAE; /* Enable DMA req. */
 
-    sdma_channel_run(DMA_REC_CH_NUM);
+    /* Begin DMA transfer */
+    rec_start_dma(addr, size);
 }
 
 void pcm_rec_dma_close(void)
diff --git a/firmware/target/arm/pcm-telechips.c b/firmware/target/arm/pcm-telechips.c
index ae4aa5ef38..3d62fcd1a9 100644
--- a/firmware/target/arm/pcm-telechips.c
+++ b/firmware/target/arm/pcm-telechips.c
@@ -33,7 +33,12 @@ struct dma_data
 {
 /* NOTE: The order of size and p is important if you use assembler
    optimised fiq handler, so don't change it. */
-    uint16_t *p;
+    union
+    {
+        uint16_t *p;
+        const void *p_r;
+        void *p_w;
+    };
     size_t size;
 #if NUM_CORES > 1
     unsigned core;
@@ -143,7 +148,7 @@ static void play_stop_pcm(void)
 
 void pcm_play_dma_start(const void *addr, size_t size)
 {
-    dma_play_data.p    = (uint16_t*)addr;
+    dma_play_data.p_r  = addr;
     dma_play_data.size = size;
 
 #if NUM_CORES > 1
@@ -248,8 +253,9 @@ void fiq_handler(void)
      * r0-r3 and r12 is a working register.
      */
     asm volatile (
-        "stmfd   sp!, { r0-r4, lr }  \n" /* stack scratch regs and lr */
-        "mov     r4, #0              \n" /* Was the callback called? */
+        "sub     lr, lr, #4          \n"
+        "stmfd   sp!, { r0-r3, lr }  \n" /* stack scratch regs and lr */
+        "mov     r14, #0             \n" /* Was the callback called? */
 #if defined(CPU_TCC780X)
         "mov     r8, #0xc000         \n" /* DAI_TX_IRQ_MASK | DAI_RX_IRQ_MASK */
         "ldr     r9, =0xf3001004     \n" /* CREQ */
@@ -260,7 +266,7 @@ void fiq_handler(void)
         "str     r8, [r9]            \n" /* clear DAI IRQs */
         "ldmia   r11, { r8-r9 }      \n" /* r8 = p, r9 = size */
         "cmp     r9, #0x10           \n" /* is size <16? */
-        "blt     .more_data          \n" /* if so, ask pcmbuf for more data */
+        "blo     .more_data          \n" /* if so, ask pcmbuf for more data */
 
     ".fill_fifo:                     \n"
         "ldr     r12, [r8], #4       \n" /* load two samples */
@@ -282,29 +288,30 @@ void fiq_handler(void)
         "sub     r9, r9, #0x10       \n" /* 4 words written */
         "stmia   r11, { r8-r9 }      \n" /* save p and size */
 
-        "cmp     r4, #0              \n" /* Callback called? */
-        "beq     .exit               \n"
-        /* "mov     r4, #0              \n" If get_more could be called multiple times! */
-        "ldr     r2, =pcm_play_dma_started\n"
-        "ldr     r2, [r2]            \n"
-        "cmp     r2, #0              \n"
-        "blxne   r2                  \n"
+        "cmp     r14, #0             \n" /* Callback called? */
+        "ldmeqfd sp!, { r0-r3, pc }^ \n" /* no? -> exit */
 
-    ".exit:                          \n"
-        "ldmfd   sp!, { r0-r4, lr }  \n"
-        "subs    pc, lr, #4          \n" /* FIQ specific return sequence */
+        "ldr     r1, =pcm_play_status_callback \n"
+        "ldr     r1, [r1]            \n"
+        "cmp     r1, #0              \n"
+        "movne   r0, %1              \n"
+        "blxne   r1                  \n"
+        "ldmfd   sp!, { r0-r3, pc }^ \n" /* exit */
 
     ".more_data:                     \n"
-        "mov     r4, #1              \n" /* Remember we got more data in this FIQ */
-        "ldr     r2, =pcm_play_get_more_callback \n"
-        "mov     r0, r11             \n" /* r0 = &p */
-        "add     r1, r11, #4         \n" /* r1 = &size */
-        "blx     r2                  \n" /* call pcm_play_get_more_callback */
-        "ldmia   r11, { r8-r9 }      \n" /* load new p and size */
-        "cmp     r9, #0x10           \n" /* did we actually get enough data? */
-        "bpl     .fill_fifo          \n" /* not stop and enough? refill */
-        "b       .exit               \n"
+        "mov     r14, #1             \n" /* Remember we got more data in this FIQ */
+        "mov     r0, %0              \n" /* r0 = status */
+        "mov     r1, r11             \n" /* r1 = &dma_play_data.p_r */
+        "add     r2, r11, #4         \n" /* r2 = &dma_play_data.size */
+        "mov     lr, pc              \n"
+        "ldr     pc, =pcm_play_dma_complete_callback \n"
+        "cmp     r0, #0              \n" /* any more to play? */
+        "ldmneia r11, { r8-r9 }      \n" /* load new p and size */
+        "cmpne   r9, #0x0f           \n" /* did we actually get enough data? */
+        "bhi     .fill_fifo          \n" /* not stop and enough? refill */
+        "ldmfd   sp!, { r0-r3, pc }^ \n" /* exit */
         ".ltorg                      \n"
+        : : "i"(PCM_DMAST_OK), "i"(PCM_DMAST_STARTED)
     );
 }
 #else /* C version for reference */
@@ -316,9 +323,8 @@ void fiq_handler(void)
     if (dma_play_data.size < 16)
     {
         /* p is empty, get some more data */
-        new_buffer = true;
-        pcm_play_get_more_callback((void**)&dma_play_data.p,
-                                   &dma_play_data.size);
+        new_buffer = pcm_play_dma_complete_callback(&dma_play_data.p_r,
+                                                    &dma_play_data.size);
     }
 
     if (dma_play_data.size >= 16)
@@ -339,7 +345,7 @@ void fiq_handler(void)
     CREQ = DAI_TX_IRQ_MASK | DAI_RX_IRQ_MASK;
 
     if (new_buffer)
-        pcm_play_dma_started_callback();
+        pcm_play_dma_status_callback(PCM_DMAST_STARTED);
 }
 #endif
 
diff --git a/firmware/target/arm/pnx0101/pcm-pnx0101.c b/firmware/target/arm/pnx0101/pcm-pnx0101.c
index 89d56af374..bb11ad32fe 100644
--- a/firmware/target/arm/pnx0101/pcm-pnx0101.c
+++ b/firmware/target/arm/pnx0101/pcm-pnx0101.c
@@ -28,7 +28,7 @@
 short __attribute__((section(".dmabuf"))) dma_buf_left[DMA_BUF_SAMPLES];
 short __attribute__((section(".dmabuf"))) dma_buf_right[DMA_BUF_SAMPLES];
 
-unsigned short* p IBSS_ATTR;
+const int16_t* p IBSS_ATTR;
 size_t p_size IBSS_ATTR;
 
 void pcm_play_lock(void)
@@ -41,7 +41,7 @@ void pcm_play_unlock(void)
 
 void pcm_play_dma_start(const void *addr, size_t size)
 {
-    p = (unsigned short*)addr;
+    p = addr;
     p_size = size;
 }
 
@@ -69,7 +69,7 @@ static inline void fill_dma_buf(int offset)
         do
         {
             int count;
-            unsigned short *tmp_p;
+            const int16_t *tmp_p;
             count = MIN(p_size / 4, (size_t)(lend - l));
             tmp_p = p;
             p_size -= count * 4;
@@ -109,16 +109,14 @@ static inline void fill_dma_buf(int offset)
             if (new_buffer)
             {
                 new_buffer = false;
-                pcm_play_dma_started_callback();
+                pcm_play_dma_status_callback(PCM_DMAST_STARTED);
             }
 
             if (l >= lend)
                 return;
 
-            pcm_play_get_more_callback((void**)&p, &p_size);
-
-            if (p_size)
-                new_buffer = true;
+            new_buffer = pcm_play_dma_complete_callback(PCM_DMAST_OK,
+                                                        &p, &p_size);
         }
         while (p_size);
     }
diff --git a/firmware/target/arm/pp/pcm-pp.c b/firmware/target/arm/pp/pcm-pp.c
index 1b38994f7b..99d46a6096 100644
--- a/firmware/target/arm/pp/pcm-pp.c
+++ b/firmware/target/arm/pp/pcm-pp.c
@@ -30,26 +30,6 @@
 
 /** DMA **/
 
-#ifdef CPU_PP502x
-/* 16-bit, L-R packed into 32 bits with left in the least significant halfword */
-#define SAMPLE_SIZE   16
-/* DMA Requests from IIS, Memory to peripheral, single transfer,
-   wait for DMA request, interrupt on complete */
-#define DMA_PLAY_CONFIG ((DMA_REQ_IIS << DMA_CMD_REQ_ID_POS) | \
-                          DMA_CMD_RAM_TO_PER | DMA_CMD_SINGLE | \
-                          DMA_CMD_WAIT_REQ | DMA_CMD_INTR)
-/* DMA status cannot be viewed from outside code in control because that can
- * clear the interrupt from outside the handler and prevent the handler from
- * from being called. Split up transfers to a reasonable size that is good as
- * a timer, obtaining a keyclick position and peaking yet still keeps the
- * FIQ count low.
- */
-#define MAX_DMA_CHUNK_SIZE (pcm_curr_sampr >> 6) /* ~1/256 seconds */
-#else
-/* 32-bit, one left 32-bit sample followed by one right 32-bit sample */
-#define SAMPLE_SIZE   32
-#endif
-
 struct dma_data
 {
 /* NOTE: The order of size and p is important if you use assembler
@@ -57,6 +37,8 @@ struct dma_data
     union
     {
         unsigned long addr;
+        const void *p_r;
+        void *p_w;
         uint32_t *p16;  /* For packed 16-16 stereo pairs */
         uint16_t *p32;  /* For individual samples converted to 32-bit */
     };
@@ -113,56 +95,208 @@ void pcm_dma_apply_settings(void)
 }
 
 #if defined(CPU_PP502x)
-/* NOTE: direct stack use forbidden by GCC stack handling bug for FIQ */
-void ICODE_ATTR __attribute__((interrupt("FIQ"))) fiq_playback(void)
+/* 16-bit, L-R packed into 32 bits with left in the least significant halfword */
+#define SAMPLE_SIZE   16
+/* DMA Requests from IIS, Memory to peripheral, single transfer,
+   wait for DMA request, interrupt on complete */
+#define DMA_PLAY_CONFIG ((DMA_REQ_IIS << DMA_CMD_REQ_ID_POS) | \
+                          DMA_CMD_RAM_TO_PER | DMA_CMD_SINGLE | \
+                          DMA_CMD_WAIT_REQ | DMA_CMD_INTR)
+/* DMA status cannot be viewed from outside code in control because that can
+ * clear the interrupt from outside the handler and prevent the handler from
+ * from being called. Split up transfers to a reasonable size that is good as
+ * a timer and peaking yet still keeps the FIQ count low.
+ */
+#define MAX_DMA_CHUNK_SIZE (pcm_curr_sampr >> 6) /* ~1/256 seconds */
+
+static inline void dma_tx_init(void)
+{
+    /* Enable DMA controller */
+    DMA_MASTER_CONTROL |= DMA_MASTER_CONTROL_EN;
+    /* FIQ priority for DMA */
+    CPU_INT_PRIORITY |= DMA_MASK;
+    /* Enable request?? Not setting or clearing everything doesn't seem to
+     * prevent it operating. Perhaps important for reliability (how requests
+     * are handled). */
+    DMA_REQ_STATUS |= 1ul << DMA_REQ_IIS;
+    DMA0_STATUS;
+}
+
+static inline void dma_tx_setup(void)
+{
+    /* Setup DMA controller */
+    DMA0_PER_ADDR = (unsigned long)&IISFIFO_WR;
+    DMA0_FLAGS = DMA_FLAGS_UNK26;
+    DMA0_INCR = DMA_INCR_RANGE_FIXED | DMA_INCR_WIDTH_32BIT;
+}
+
+static inline unsigned long dma_tx_buf_prepare(const void *addr)
+{
+    unsigned long a = (unsigned long)addr;
+
+    if (a < UNCACHED_BASE_ADDR) {
+        /* VA in DRAM - writeback all data and get PA */
+        a = UNCACHED_ADDR(a);
+        commit_dcache();
+    }
+
+    return a;
+}
+
+static inline void dma_tx_start(bool begin)
+{
+    size_t size = MAX_DMA_CHUNK_SIZE;
+
+    /* Not at least MAX_DMA_CHUNK_SIZE left or there would be less
+     * than a FIFO's worth of data after this transfer? */
+    if (size + 16*4 > dma_play_data.size)
+        size = dma_play_data.size;
+
+    /* Set the new DMA values and activate channel */
+    DMA0_RAM_ADDR = dma_play_data.addr;
+    DMA0_CMD = DMA_PLAY_CONFIG | (size - 4) | DMA_CMD_START;
+
+    (void)begin;
+}
+
+static void dma_tx_stop(void)
+{
+    unsigned long status = DMA0_STATUS; /* Snapshot- resume from this point */
+    unsigned long cmd = DMA0_CMD;
+    size_t size = 0;
+
+    /* Stop transfer */
+    DMA0_CMD = cmd & ~(DMA_CMD_START | DMA_CMD_INTR);
+
+    /* Wait for not busy + clear int */
+    while (DMA0_STATUS & (DMA_STATUS_BUSY | DMA_STATUS_INTR));
+
+    if (status & DMA_STATUS_BUSY) {
+        /* Transfer was interrupted - leave what's left */
+        size = (cmd & 0xfffc) - (status & 0xfffc);
+    }
+    else if (status & DMA_STATUS_INTR) {
+        /* Transfer was finished - DMA0_STATUS will have been reloaded
+         * automatically with size in DMA0_CMD. Setup to restart on next
+         * segment. */
+        size = (cmd & 0xfffc) + 4;
+    }
+    /* else not an active state - size = 0 */
+
+    dma_play_data.addr += size;
+    dma_play_data.size -= size;
+
+    if (dma_play_data.size == 0)
+        dma_play_data.addr = 0; /* Entire buffer has completed. */
+}
+
+static inline void dma_tx_lock(void)
+{
+    CPU_INT_DIS = DMA_MASK;
+}
+
+static inline void dma_tx_unlock(void)
 {
-    bool new_buffer = false;
-    register size_t size;
+    CPU_INT_EN = DMA_MASK;
+}
 
+/* NOTE: direct stack use forbidden by GCC stack handling bug for FIQ */
+void fiq_playback(void) ICODE_ATTR __attribute__((interrupt("FIQ")));
+void fiq_playback(void)
+{
     DMA0_STATUS; /* Clear any pending interrupt */
 
-    size = (DMA0_CMD & 0xffff) + 4; /* Get size of trasfer that caused this
-                                       interrupt */
+    size_t size = (DMA0_CMD & 0xffff) + 4; /* Get size of trasfer that caused
+                                              this interrupt */
     dma_play_data.addr += size;
     dma_play_data.size -= size;
 
-    while (1)
-    {
-        if (dma_play_data.size > 0) {
-            size = MAX_DMA_CHUNK_SIZE;
-            /* Not at least MAX_DMA_CHUNK_SIZE left or there would be less
-             * than a FIFO's worth of data after this transfer? */
-            if (size + 16*4 > dma_play_data.size)
-                size = dma_play_data.size;
-
-            /* Set the new DMA values and activate channel */
-            DMA0_RAM_ADDR = dma_play_data.addr;
-            DMA0_CMD = DMA_PLAY_CONFIG | (size - 4) | DMA_CMD_START;
-
-            if (new_buffer)
-                pcm_play_dma_started_callback();
-            return;
-        }
+    if (LIKELY(dma_play_data.size != 0)) {
+        /* Begin next segment */
+        dma_tx_start(false);
+    }
+    else if (pcm_play_dma_complete_callback(PCM_DMAST_OK, &dma_play_data.p_r,
+                                            &dma_play_data.size)) {
+        dma_play_data.addr = dma_tx_buf_prepare(dma_play_data.p_r);
+        dma_tx_start(false);
+        pcm_play_dma_status_callback(PCM_DMAST_STARTED);
+    }
+}
 
-        new_buffer = true;
+#else /* !defined (CPU_PP502x) */
 
-        /* Buffer empty.  Try to get more. */
-        pcm_play_get_more_callback((void **)&dma_play_data.addr,
-                                   &dma_play_data.size);
+/* 32-bit, one left 32-bit sample followed by one right 32-bit sample */
+#define SAMPLE_SIZE   32
 
-        if (dma_play_data.size == 0) {
-            /* No more data */
-            return;
-        }
+static void dma_tx_init(void)
+{
+    /* Set up banked registers for FIQ mode */
 
-        if (dma_play_data.addr < UNCACHED_BASE_ADDR) {
-            /* Flush any pending cache writes */
-            dma_play_data.addr = UNCACHED_ADDR(dma_play_data.addr);
-            commit_dcache();
-        }
+    /* Use non-banked registers for scratch. */
+    register volatile void *iiscfg asm("r0") = &IISCONFIG;
+    register volatile void *dmapd asm("r1") = &dma_play_data;
+
+    asm volatile (
+        "mrs    r2, cpsr            \n" /* Save mode and interrupt status */
+        "msr    cpsr_c, #0xd1       \n" /* Switch to FIQ mode */
+        "mov    r8, #0              \n"
+        "mov    r9, #0              \n"
+        "mov    r10, %[iiscfg]      \n"
+        "mov    r11, %[dmapd]       \n"
+        "msr    cpsr_c, r2          \n"
+        :
+        : [iiscfg]"r"(iiscfg), [dmapd]"r"(dmapd)
+        : "r2");
+
+    /* FIQ priority for I2S */
+    CPU_INT_PRIORITY |= IIS_MASK;
+    CPU_INT_EN = IIS_MASK;
+}
+
+static inline void dma_tx_setup(void)
+{
+    /* Nothing to do */
+}
+
+static inline unsigned long dma_tx_buf_prepare(const void *addr)
+{
+    return (unsigned long)addr;
+}
+
+static inline void dma_tx_start(bool begin)
+{
+    if (begin) {
+        IISCONFIG &= ~IIS_TXFIFOEN; /* Stop transmitting */
     }
+
+    /* Fill the FIFO or start when data is used up */
+    while (IIS_TX_FREE_COUNT >= 2 && dma_play_data.size != 0) {
+        IISFIFO_WRH = *dma_play_data.p32++;
+        IISFIFO_WRH = *dma_play_data.p32++;
+        dma_play_data.size -= 4;
+    }
+
+    if (begin) {
+        IISCONFIG |= IIS_TXFIFOEN; /* Start transmitting */
+    }
+}
+
+static inline void dma_tx_stop(void)
+{
+    /* Disable TX interrupt */
+    IIS_IRQTX_REG &= ~IIS_IRQTX;
+}
+
+static inline void dma_tx_lock(void)
+{
+    IIS_IRQTX_REG &= ~IIS_IRQTX;
+}
+
+static inline void dma_tx_unlock(void)
+{
+    IIS_IRQTX_REG |= IIS_IRQTX;
 }
-#else
+
 /* ASM optimised FIQ handler. Checks for the minimum allowed loop cycles by
  * evalutation of free IISFIFO-slots against available source buffer words.
  * Through this it is possible to move the check for IIS_TX_FREE_COUNT outside
@@ -173,150 +307,123 @@ void ICODE_ATTR __attribute__((interrupt("FIQ"))) fiq_playback(void)
  * ASM implementation (not used anymore): GCC fails to make use of the fact
  * that FIQ mode has registers r8-r14 banked, and so does not need to be saved.
  * This routine uses only these registers, and so will never touch the stack
- * unless it actually needs to do so when calling pcm_callback_for_more.
+ * unless it actually needs to do so when calling pcm_play_dma_complete_callback.
  * C version is still included below for reference and testing.
  */
 #if 1
 void fiq_playback(void) ICODE_ATTR __attribute__((naked));
 void fiq_playback(void)
 {
-    /* r10 contains IISCONFIG address (set in crt0.S to minimise code in actual
-     * FIQ handler. r11 contains address of p (also set in crt0.S). Most other
-     * addresses we need are generated by using offsets with these two.
-     * r10 + 0x40 is IISFIFO_WR, and r10 + 0x0c is IISFIFO_CFG.
-     * r8 and r9 contains local copies of p and size respectively.
-     * r0-r3 and r12 is a working register.
+    /* r8 and r9 contains local copies of p and size respectively.
+     * r10 contains IISCONFIG address (set during PCM init to minimize code in
+     * FIQ handler.Most other addresses we need are generated by using offsets
+     * from this.
+     * r10 + 0x40 is IISFIFO_WR, and r10 + 0x1c is IISFIFO_CFG.
+     * r11 contains address of dma_play_data
+     * r12 and r14 are working registers.
+     *
+     * Divided into two blocks: one where no external calls are needed and
+     * one where external callbacks are made
      */
     asm volatile (
-        "stmfd   sp!, { r0-r4, lr }  \n" /* stack scratch regs and lr */
-
-        "mov     r4, #0              \n" /* Was the callback called? */
-#if CONFIG_CPU == PP5002
-        "ldr     r12, =0xcf001040    \n" /* Some magic from iPodLinux */
-        "ldr     r12, [r12]          \n"
-#endif
-        "ldmia   r11, { r8-r9 }      \n" /* r8 = p, r9 = size */
-        "cmp     r9, #0              \n" /* is size 0? */
-        "beq     .more_data          \n" /* if so, ask pcmbuf for more data */
-
-#if SAMPLE_SIZE == 16
-    ".check_fifo:                    \n"   
-        "ldr     r0, [r10, %[cfg]]   \n" /* read IISFIFO_CFG to check FIFO status */
-        "and     r0, r0, %[mask]     \n" /* r0 = IIS_TX_FREE_COUNT << 16 (PP502x) */
-
-        "mov     r1, r0, lsr #16     \n" /* number of free FIFO slots */
-        "cmp     r1, r9, lsr #2      \n" /* number of words from source */
-        "movgt   r1, r9, lsr #2      \n" /* r1 = amount of allowed loops */
-        "sub     r9, r9, r1, lsl #2  \n" /* r1 words will be written in following loop */
-
-        "subs    r1, r1, #2          \n"
-    ".fifo_loop_2:                   \n"
-        "ldmgeia r8!, {r2, r12}      \n" /* load four samples */
-        "strge   r2 , [r10, %[wr]]   \n" /* write sample 0-1 to IISFIFO_WR */
-        "strge   r12, [r10, %[wr]]   \n" /* write sample 2-3 to IISFIFO_WR */
-        "subges  r1, r1, #2          \n" /* one more loop? */
-        "bge     .fifo_loop_2        \n" /* yes, continue */
-
-        "tst     r1, #1              \n" /* two samples (one word) left? */
-        "ldrne   r12, [r8], #4       \n" /* load two samples */
-        "strne   r12, [r10, %[wr]]   \n" /* write sample 0-1 to IISFIFO_WR */
-#elif SAMPLE_SIZE == 32
-    ".check_fifo:                    \n"
-        "ldr     r0, [r10, %[cfg]]   \n" /* read IISFIFO_CFG to check FIFO status */
-        "and     r0, r0, %[mask]     \n" /* r0 = IIS_TX_FREE_COUNT << 23 (PP5002) */
-
-        "movs    r1, r0, lsr #24     \n" /* number of free pairs of FIFO slots */
-        "beq     .fifo_fill_complete \n" /* no complete pair? -> exit */
-        "cmp     r1, r9, lsr #2      \n" /* number of words from source */
-        "movgt   r1, r9, lsr #2      \n" /* r1 = amount of allowed loops */
-        "sub     r9, r9, r1, lsl #2  \n" /* r1 words will be written in following loop */
-
-    ".fifo_loop:                     \n"
-        "ldr     r12, [r8], #4       \n" /* load two samples */
-        "mov     r2 , r12, lsl #16   \n" /* put left sample at the top bits */
-        "str     r2 , [r10, %[wr]]   \n" /* write top sample to IISFIFO_WR */
-        "str     r12, [r10, %[wr]]   \n" /* write low sample to IISFIFO_WR*/
-        "subs    r1, r1, #1          \n" /* one more loop? */
-        "bgt     .fifo_loop          \n" /* yes, continue */
-
-    ".fifo_fill_complete:            \n"
-#endif
-        "cmp     r4, #0              \n" /* If fill came after get_more... */
-        "beq     .still_old_buffer   \n"
-        "mov     r4, #0              \n"
-        "ldr     r2, =pcm_play_dma_started \n"
-        "ldrne   r2, [r2]            \n"
-        "cmp     r2, #0              \n"
-        "movne   lr, pc              \n"
-        "bxne    r2                  \n"
-
-    ".still_old_buffer:              \n"
-        "cmp     r9, #0              \n" /* either FIFO is full or source buffer is empty */
-        "bgt     .exit               \n" /* if source buffer is not empty, FIFO must be full */
-
-    ".more_data:                     \n"
-        "mov     r4, #1              \n" /* Remember we did this */
-        "ldr     r2, =pcm_play_get_more_callback \n"
-        "mov     r0, r11             \n" /* r0 = &p */
-        "add     r1, r11, #4         \n" /* r1 = &size */
-        "mov     lr, pc              \n" /* call pcm_play_get_more_callback */
-        "bx      r2                  \n"
-        "ldmia   r11, { r8-r9 }      \n" /* load new p and size */
-        "cmp     r9, #0              \n"
-        "bne     .check_fifo         \n" /* size != 0? refill */
-
-    ".exit:                          \n" /* (r9=0 if stopping, look above) */
-        "stmia   r11, { r8-r9 }      \n" /* save p and size */
-        "ldmfd   sp!, { r0-r4, lr }  \n"
-        "subs    pc, lr, #4          \n" /* FIQ specific return sequence */
-        ".ltorg                      \n"
+    /* No external calls */
+        "sub     lr, lr, #4           \n" /* Prepare return address */
+        "stmfd   sp!, { lr }          \n" /* stack lr so we can use it */
+        "ldr     r12, =0xcf001040     \n" /* Some magic from iPodLinux ... */
+        "ldr     r12, [r12]           \n" /* ... actually a DMA INT ack? */
+        "ldmia   r11, { r8-r9 }       \n" /* r8 = p, r9 = size */
+        "cmp     r9, #0               \n" /* is size 0? */
+        "beq     1f                   \n" /* if so, ask PCM for more data */
+
+        "ldr     r14, [r10, #0x1c]    \n" /* read IISFIFO_CFG to check FIFO status */
+        "and     r14, r14, #(0xe<<23) \n" /* r14 = (IIS_TX_FREE_COUNT & ~1) << 23 */
+        "cmp     r9, r14, lsr #22     \n" /* number of words from source */
+        "movlo   r14, r9, lsl #22     \n" /* r14 = amount of allowed loops */
+        "sub     r9, r9, r14, lsr #22 \n" /* r14 words will be written in loop */
+    "0:                               \n"
+        "ldr     r12, [r8], #4        \n" /* load left-right pair */
+        "subs    r14, r14, #(0x2<<23) \n" /* one more loop? ... */
+        "strh    r12, [r10, #0x40]    \n" /* left sample to IISFIFO_WR */
+        "mov     r12, r12, lsr #16    \n" /* put right sample in bottom 16 bits */
+        "strh    r12, [r10, #0x40]    \n" /* right sample to IISFIFO_WR */
+        "bhi     0b                   \n" /* ... yes, continue */
+
+        "cmp     r9, #0               \n" /* either FIFO full or size empty? */
+        "stmneia r11, { r8-r9 }       \n" /* save p and size, if not empty */
+        "ldmnefd sp!, { pc }^         \n" /* RFE if not empty */
+
+    /* Making external calls */
+    "1:                               \n"
+        "stmfd   sp!, { r0-r3 }       \n" /* Must save volatiles */
+    "2:                               \n"
+        "mov     r0, %0               \n" /* r0 = status */
+        "mov     r1, r11              \n" /* r1 = &dma_play_data.p_r */
+        "add     r2, r11, #4          \n" /* r2 = &dma_play_data.size */
+        "ldr     r3, =pcm_play_dma_complete_callback \n"
+        "mov     lr, pc               \n" /* long call (not in same section) */
+        "bx      r3                   \n"
+        "cmp     r0, #0               \n" /* more data? */
+        "ldmeqfd sp!, { r0-r3, pc }^  \n" /* no? -> exit */
+
+        "ldr     r14, [r10, #0x1c]    \n" /* read IISFIFO_CFG to check FIFO status */
+        "ands    r14, r14, #(0xe<<23) \n" /* r14 = (IIS_TX_FREE_COUNT & ~1) << 23 */
+        "bne     4f                   \n"
+    "3:                               \n" /* inform of started status if registered */
+        "ldr     r1, =pcm_play_status_callback \n"
+        "ldr     r1, [r1]             \n"
+        "cmp     r1, #0               \n"
+        "movne   r0, %1               \n"
+        "movne   lr, pc               \n"
+        "bxne    r1                   \n"
+        "ldmfd   sp!, { r0-r3, pc }^  \n" /* exit */
+    "4:                               \n"
+        "ldmia   r11, { r8-r9 }       \n" /* load new p and size */
+        "cmp     r9, r14, lsr #22     \n" /* number of words from source */
+        "movlo   r14, r9, lsl #22     \n" /* r14 = amount of allowed loops */
+        "sub     r9, r9, r14, lsr #22 \n" /* r14 words will be written in loop */
+    "0:                               \n"
+        "ldr     r12, [r8], #4        \n" /* load left-right pair */
+        "subs    r14, r14, #(0x2<<23) \n" /* one more loop? ... */
+        "strh    r12, [r10, #0x40]    \n" /* left sample to IISFIFO_WR */
+        "mov     r12, r12, lsr #16    \n" /* put right sample in bottom 16 bits */
+        "strh    r12, [r10, #0x40]    \n" /* right sample to IISFIFO_WR */
+        "bhi     0b                   \n" /* ... yes, continue */
+        "stmia   r11, { r8-r9 }       \n" /* save p and size */
+
+        "cmp     r9, #0               \n" /* used up data in FIFO fill? */
+        "bne     3b                   \n" /* no? -> go return */
+        "b       2b                   \n" /* yes -> get even more */
+        ".ltorg                       \n"
         : /* These must only be integers! No regs */
-        : [mask]"i"(IIS_TX_FREE_MASK),
-          [cfg]"i"((int)&IISFIFO_CFG - (int)&IISCONFIG),
-          [wr]"i"((int)&IISFIFO_WR - (int)&IISCONFIG)
-    );
+        : "i"(PCM_DMAST_OK), "i"(PCM_DMAST_STARTED));
 }
+
 #else /* C version for reference */
-void fiq_playback(void) __attribute__((interrupt ("FIQ"))) ICODE_ATTR;
+
 /* NOTE: direct stack use forbidden by GCC stack handling bug for FIQ */
+void fiq_playback(void) ICODE_ATTR __attribute__((interrupt ("FIQ")));
 void fiq_playback(void)
 {
-    bool new_buffer = false;
-
-#if CONFIG_CPU == PP5002
     inl(0xcf001040);
-#endif
 
-    do {
-        while (dma_play_data.size > 0) {
-            if (IIS_TX_FREE_COUNT < 2) {
-                if (new_buffer) {
-                    new_buffer = false;
-                    pcm_play_dma_started_callback();
-                }
-                return;
-            }
-#if SAMPLE_SIZE == 16
-            IISFIFO_WR = *dma_play_data.p16++;
-#elif SAMPLE_SIZE == 32
-            IISFIFO_WR = *dma_play_data.p32++ << 16;
-            IISFIFO_WR = *dma_play_data.p32++ << 16;
-#endif
-            dma_play_data.size -= 4;
-        }
+    if (LIKELY(dma_play_data.size != 0)) {
+        dma_tx_start(false);
 
-        if (new_buffer) {
-            new_buffer = false;
-            pcm_play_dma_started_callback();
+        if (dma_play_data.size != 0) {
+            /* Still more data */
+            return;
         }
+    }
 
-        /* p is empty, get some more data */
-        pcm_play_get_more_callback((void **)&dma_play_data.addr,
-                                   &dma_play_data.size);
-        new_buffer = true;
-    } while (dma_play_data.size);
+    while (pcm_play_dma_complete_callback(PCM_DMAST_OK, &dma_play_data.p_r,
+                                          &dma_play_data.size)) {
+        dma_tx_start(false);
+        pcm_play_dma_status_callback(PCM_DMAST_STARTED);
 
-    /* No more data  */
+        if (dma_play_data.size != 0) {
+            return;
+        }
+    }
 }
 #endif /* ASM / C selection */
 #endif /* CPU_PP502x */
@@ -329,11 +436,7 @@ void pcm_play_lock(void)
     int status = disable_fiq_save();
 
     if (++dma_play_data.locked == 1) {
-#ifdef CPU_PP502x
-        CPU_INT_DIS = DMA_MASK;
-#else
-        IIS_IRQTX_REG &= ~IIS_IRQTX;
-#endif
+        dma_tx_lock();
     }
 
     restore_fiq(status);
@@ -341,89 +444,25 @@ void pcm_play_lock(void)
 
 void pcm_play_unlock(void)
 {
-   int status = disable_fiq_save();
+    int status = disable_fiq_save();
 
     if (--dma_play_data.locked == 0 && dma_play_data.state != 0) {
-#ifdef CPU_PP502x
-        CPU_INT_EN = DMA_MASK;
-#else
-        IIS_IRQTX_REG |= IIS_IRQTX;
-#endif
+        dma_tx_unlock();
     }
 
-   restore_fiq(status);
+    restore_fiq(status);
 }
 
 static void play_start_pcm(void)
 {
     fiq_function = fiq_playback;
-
-#ifdef CPU_PP502x
-    /* Not at least MAX_DMA_CHUNK_SIZE left or there would be less than a
-     * FIFO's worth of data after this transfer? */
-    size_t size = MAX_DMA_CHUNK_SIZE;
-    if (size + 16*4 > dma_play_data.size)
-        size = dma_play_data.size;
-
-    DMA0_RAM_ADDR = dma_play_data.addr;
-    DMA0_CMD = DMA_PLAY_CONFIG | (size - 4) | DMA_CMD_START;
     dma_play_data.state = 1;
-#else
-    IISCONFIG &= ~IIS_TXFIFOEN;  /* Stop transmitting */
-
-    /* Fill the FIFO or start when data is used up */
-    while (1) {
-        if (IIS_TX_FREE_COUNT < 2 || dma_play_data.size == 0) {
-            IISCONFIG |= IIS_TXFIFOEN; /* Start transmitting */
-            dma_play_data.state = 1;
-            return;
-        }
-
-#if SAMPLE_SIZE == 16
-        IISFIFO_WR = *dma_play_data.p16++;
-#elif SAMPLE_SIZE == 32
-        IISFIFO_WR = *dma_play_data.p32++ << 16;
-        IISFIFO_WR = *dma_play_data.p32++ << 16;
-#endif
-        dma_play_data.size -= 4;
-    }
-#endif
+    dma_tx_start(true);
 }
 
 static void play_stop_pcm(void)
 {
-#ifdef CPU_PP502x
-    unsigned long status = DMA0_STATUS; /* Snapshot- resume from this point */
-    unsigned long cmd = DMA0_CMD;
-    size_t size = 0;
-
-    /* Stop transfer */
-    DMA0_CMD = cmd & ~(DMA_CMD_START | DMA_CMD_INTR);
-
-    /* Wait for not busy + clear int */
-    while (DMA0_STATUS & (DMA_STATUS_BUSY | DMA_STATUS_INTR));
-
-    if (status & DMA_STATUS_BUSY) {
-        /* Transfer was interrupted - leave what's left */
-        size = (cmd & 0xfffc) - (status & 0xfffc);
-    }
-    else if (status & DMA_STATUS_INTR) {
-        /* Transfer was finished - DMA0_STATUS will have been reloaded
-         * automatically with size in DMA0_CMD. Setup to restart on next
-         * segment. */
-        size = (cmd & 0xfffc) + 4;
-    }
-    /* else not an active state - size = 0 */
-
-    dma_play_data.addr += size;
-    dma_play_data.size -= size;
-
-    if (dma_play_data.size == 0)
-        dma_play_data.addr = 0; /* Entire buffer has completed. */
-#else
-    /* Disable TX interrupt */
-    IIS_IRQTX_REG &= ~IIS_IRQTX;
-#endif
+    dma_tx_stop();
 
     /* Wait for FIFO to empty */
     while (!IIS_TX_IS_EMPTY);
@@ -433,30 +472,17 @@ static void play_stop_pcm(void)
 
 void pcm_play_dma_start(const void *addr, size_t size)
 {
+    pcm_play_dma_stop();
+
 #if NUM_CORES > 1
     /* This will become more important later - and different ! */
     dma_play_data.core = processor_id(); /* save initiating core */
 #endif
 
-    pcm_play_dma_stop();
-
-#ifdef CPU_PP502x
-    if ((unsigned long)addr < UNCACHED_BASE_ADDR) {
-        /* Flush any pending cache writes */
-        addr = UNCACHED_ADDR(addr);
-        commit_dcache();
-    }
+    dma_tx_setup();
 
-    dma_play_data.addr = (unsigned long)addr;
+    dma_play_data.addr = dma_tx_buf_prepare(addr);
     dma_play_data.size = size;
-    DMA0_PER_ADDR = (unsigned long)&IISFIFO_WR;
-    DMA0_FLAGS = DMA_FLAGS_UNK26;
-    DMA0_INCR = DMA_INCR_RANGE_FIXED | DMA_INCR_WIDTH_32BIT;
-#else
-    dma_play_data.addr = (unsigned long)addr;
-    dma_play_data.size = size;
-#endif
-
     play_start_pcm();
 }
 
@@ -490,39 +516,7 @@ void pcm_play_dma_init(void)
     /* Initialize default register values. */
     audiohw_init();
 
-#ifdef CPU_PP502x
-    /* Enable DMA controller */
-    DMA_MASTER_CONTROL |= DMA_MASTER_CONTROL_EN;
-    /* FIQ priority for DMA */
-    CPU_INT_PRIORITY |= DMA_MASK;
-    /* Enable request?? Not setting or clearing everything doesn't seem to
-     * prevent it operating. Perhaps important for reliability (how requests
-     * are handled). */
-    DMA_REQ_STATUS |= 1ul << DMA_REQ_IIS;
-    DMA0_STATUS;
-#else
-    /* Set up banked registers for FIQ mode */
-
-    /* Use non-banked registers for scratch. */
-    register volatile void *iiscfg asm("r0") = &IISCONFIG;
-    register volatile void *dmapd asm("r1") = &dma_play_data;
-
-    asm volatile (
-        "mrs    r2, cpsr            \n" /* Save mode and interrupt status */
-        "msr    cpsr_c, #0xd1       \n" /* Switch to FIQ mode */
-        "mov    r8, #0              \n"
-        "mov    r9, #0              \n"
-        "mov    r10, %[iiscfg]      \n"
-        "mov    r11, %[dmapd]       \n"
-        "msr    cpsr_c, r2          \n"
-        :
-        : [iiscfg]"r"(iiscfg), [dmapd]"r"(dmapd)
-        : "r2");
-
-    /* FIQ priority for I2S */
-    CPU_INT_PRIORITY |= IIS_MASK;
-    CPU_INT_EN = IIS_MASK;
-#endif
+    dma_tx_init();
 
     IISCONFIG |= IIS_TXFIFOEN;
 }
@@ -649,11 +643,15 @@ void fiq_record(void)
         }
     }
 
-    pcm_rec_more_ready_callback(0, (void *)&dma_rec_data.addr,
-                                &dma_rec_data.size);
+    if (pcm_rec_dma_complete_callback(PCM_DMAST_OK, &dma_rec_data.p_w,
+                                      &dma_rec_data.size))
+    {
+        pcm_rec_dma_status_callback(PCM_DMAST_STARTED);
+    }
 }
 
-#else
+#else /* !(SANSA_C200 || SANSA_E200) */
+
 void fiq_record(void)
 {
     while (dma_rec_data.size > 0) {
@@ -664,17 +662,20 @@ void fiq_record(void)
 #if SAMPLE_SIZE == 16
         *dma_rec_data.p16++ = IISFIFO_RD;
 #elif SAMPLE_SIZE == 32
-        *dma_rec_data.p32++ = IISFIFO_RD >> 16;
-        *dma_rec_data.p32++ = IISFIFO_RD >> 16;
+        *dma_rec_data.p32++ = IISFIFO_RDH;
+        *dma_rec_data.p32++ = IISFIFO_RDH;
 #endif
         dma_rec_data.size -= 4;
     }
 
-    pcm_rec_more_ready_callback(0, (void *)&dma_rec_data.addr,
-                                &dma_rec_data.size);
+    if (pcm_rec_dma_complete_callback(PCM_DMAST_OK, &dma_rec_data.p_w,
+                                      &dma_rec_data.size))
+    {
+        pcm_rec_dma_status_callback(PCM_DMAST_STARTED);
+    }
 }
 
-#endif /* SANSA_E200 */
+#endif /* SANSA_C200 || SANSA_E200 */
 
 void pcm_rec_dma_stop(void)
 {
diff --git a/firmware/target/arm/rk27xx/pcm-rk27xx.c b/firmware/target/arm/rk27xx/pcm-rk27xx.c
index 80a8d462ea..e4318de408 100644
--- a/firmware/target/arm/rk27xx/pcm-rk27xx.c
+++ b/firmware/target/arm/rk27xx/pcm-rk27xx.c
@@ -273,15 +273,13 @@ size_t pcm_get_bytes_waiting(void)
 /* audio DMA ISR called when chunk from callers buffer has been transfered */
 void INT_HDMA(void)
 {
-    void *start;
+    const void *start;
     size_t size;
 
-    pcm_play_get_more_callback(&start, &size);
-
-    if (size != 0)
+    if (pcm_play_dma_complete_callback(PCM_DMAST_OK, &start, &size))
     {
         hdma_i2s_transfer(start, size);
-        pcm_play_dma_started_callback();
+        pcm_play_dma_status_callback(PCM_DMAST_STARTED);
     }
 }
 
diff --git a/firmware/target/arm/s3c2440/gigabeat-fx/pcm-meg-fx.c b/firmware/target/arm/s3c2440/gigabeat-fx/pcm-meg-fx.c
index 35905645dd..a1c854a0df 100644
--- a/firmware/target/arm/s3c2440/gigabeat-fx/pcm-meg-fx.c
+++ b/firmware/target/arm/s3c2440/gigabeat-fx/pcm-meg-fx.c
@@ -215,16 +215,14 @@ void pcm_play_dma_pause(bool pause)
 
 void fiq_handler(void)
 {
-    static void *start;
+    static const void *start;
     static size_t size;
 
     /* clear any pending interrupt */
     SRCPND = DMA2_MASK;
 
     /* Buffer empty.  Try to get more. */
-    pcm_play_get_more_callback(&start, &size);
-
-    if (size == 0)
+    if (!pcm_play_dma_complete_callback(PCM_DMAST_OK, &start, &size))
         return;
 
     /* Flush any pending cache writes */
@@ -237,7 +235,7 @@ void fiq_handler(void)
     /* Re-Activate the channel */
     DMASKTRIG2 = 0x2;
 
-    pcm_play_dma_started_callback();
+    pcm_play_dma_status_callback(PCM_DMAST_STARTED);
 }
 
 size_t pcm_get_bytes_waiting(void)
diff --git a/firmware/target/arm/s3c2440/mini2440/pcm-mini2440.c b/firmware/target/arm/s3c2440/mini2440/pcm-mini2440.c
index a4f58a8e06..943cbb2ade 100644
--- a/firmware/target/arm/s3c2440/mini2440/pcm-mini2440.c
+++ b/firmware/target/arm/s3c2440/mini2440/pcm-mini2440.c
@@ -255,16 +255,14 @@ void pcm_play_dma_pause(bool pause)
 
 void fiq_handler(void)
 {
-    static void *start;
+    static const void *start;
     static size_t size;
 
     /* clear any pending interrupt */
     SRCPND = DMA2_MASK;
 
     /* Buffer empty.  Try to get more. */
-    pcm_play_get_more_callback(&start, &size);
-
-    if (size == 0)
+    if (!pcm_play_dma_complete_callback(PCM_DMAST_OK, &start, &size))
         return;
 
     /* Flush any pending cache writes */
@@ -277,7 +275,7 @@ void fiq_handler(void)
     /* Re-Activate the channel */
     DMASKTRIG2 = 0x2;
 
-    pcm_play_dma_started_callback();
+    pcm_play_dma_status_callback(PCM_DMAST_STARTED);
 }
 
 size_t pcm_get_bytes_waiting(void)
diff --git a/firmware/target/arm/s5l8700/pcm-s5l8700.c b/firmware/target/arm/s5l8700/pcm-s5l8700.c
index 7b4258fa68..c5a5bcf74f 100644
--- a/firmware/target/arm/s5l8700/pcm-s5l8700.c
+++ b/firmware/target/arm/s5l8700/pcm-s5l8700.c
@@ -116,9 +116,10 @@ void INT_DMA(void)
         {
             if (!nextsize)
             {
-                pcm_play_get_more_callback((void**)&nextbuf, &nextsize);
-                if (!nextsize) break;
-                new_buffer = true;
+                new_buffer = pcm_play_dma_complete_callback(PCM_DMAST_OK,
+                                (const void**)&nextbuf, &nextsize);
+                if (!new_buffer)
+                    break;
             }
             queuedsize = MIN(sizeof(dblbuf), nextsize / 2);
             nextsize -= queuedsize;
@@ -133,7 +134,7 @@ void INT_DMA(void)
 
         if (new_buffer)
         {
-            pcm_play_dma_started_callback();
+            pcm_play_dma_status_callback(PCM_DMAST_STARTED);
             new_buffer = false;
         }
     }
diff --git a/firmware/target/arm/s5l8702/pcm-s5l8702.c b/firmware/target/arm/s5l8702/pcm-s5l8702.c
index b58ef0f4d3..1442afa420 100644
--- a/firmware/target/arm/s5l8702/pcm-s5l8702.c
+++ b/firmware/target/arm/s5l8702/pcm-s5l8702.c
@@ -65,7 +65,7 @@ void INT_DMAC0C0(void)
     DMAC0INTTCCLR = 1;
     if (!pcm_remaining)
     {
-        pcm_play_get_more_callback((void**)&dataptr, &pcm_remaining);
+        pcm_play_dma_complete_callback((const void**)&dataptr, &pcm_remaining);
         pcm_chunksize = pcm_remaining;
     }
     if (!pcm_remaining)
@@ -115,7 +115,7 @@ void INT_DMAC0C0(void)
     }
     else DMAC0C0NEXTLLI = pcm_lli;
 
-    pcm_play_dma_started_callback();
+    pcm_play_dma_status_callback(PCM_DMAST_STARTED);
 }
 
 void pcm_play_dma_start(const void* addr, size_t size)
diff --git a/firmware/target/arm/tms320dm320/mrobe-500/pcm-mr500.c b/firmware/target/arm/tms320dm320/mrobe-500/pcm-mr500.c
index 91d6b66130..d23c93de39 100644
--- a/firmware/target/arm/tms320dm320/mrobe-500/pcm-mr500.c
+++ b/firmware/target/arm/tms320dm320/mrobe-500/pcm-mr500.c
@@ -33,7 +33,7 @@
 /* This is global to save some latency when pcm_play_dma_get_peak_buffer is 
  *  called.
  */
-static void *start;
+static const void *start;
 
 void pcm_play_dma_postinit(void)
 {
@@ -164,9 +164,7 @@ void DSPHINT(void)
         
     case MSG_REFILL:
         /* Buffer empty.  Try to get more. */
-        pcm_play_get_more_callback(&start, &size);
-
-        if (size != 0)
+        if (pcm_play_dma_complete_callback(PCM_DMAST_OK, &start, &size))
         {
             unsigned long sdem_addr=(unsigned long)start - CONFIG_SDRAM_START;
             /* Flush any pending cache writes */
@@ -180,7 +178,7 @@ void DSPHINT(void)
             DEBUGF("pcm_sdram at 0x%08lx, sdem_addr 0x%08lx",
                 (unsigned long)start, (unsigned long)sdem_addr);
 
-            pcm_play_dma_started_callback();
+            pcm_play_dma_status_callback(PCM_DMAST_STARTED);
         }
         
         break;
diff --git a/firmware/target/arm/tms320dm320/sansa-connect/pcm-sansaconnect.c b/firmware/target/arm/tms320dm320/sansa-connect/pcm-sansaconnect.c
index 8b1fbf95e4..6e640bdf12 100644
--- a/firmware/target/arm/tms320dm320/sansa-connect/pcm-sansaconnect.c
+++ b/firmware/target/arm/tms320dm320/sansa-connect/pcm-sansaconnect.c
@@ -34,7 +34,7 @@
 /* This is global to save some latency when pcm_play_dma_get_peak_buffer is 
  *  called.
  */
-static void *start;
+static const void *start;
 static int dma_channel;
 
 void pcm_play_dma_postinit(void)
@@ -171,9 +171,7 @@ void DSPHINT(void)
         
     case MSG_REFILL:
         /* Buffer empty.  Try to get more. */
-        pcm_play_get_more_callback(&start, &size);
-
-        if (size != 0)
+        if (pcm_play_dma_complete_callback(PCM_DMAST_OK, &start, &size))
         {
             unsigned long sdem_addr=(unsigned long)start - CONFIG_SDRAM_START;
             /* Flush any pending cache writes */
@@ -187,7 +185,7 @@ void DSPHINT(void)
             DEBUGF("pcm_sdram at 0x%08lx, sdem_addr 0x%08lx",
                 (unsigned long)start, (unsigned long)sdem_addr);
 
-            pcm_play_dma_started_callback();
+            pcm_play_dma_status_callback(PCM_DMAST_STARTED);
         }
         
         break;
diff --git a/firmware/target/coldfire/pcm-coldfire.c b/firmware/target/coldfire/pcm-coldfire.c
index e95d445337..2e2312f7ae 100644
--- a/firmware/target/coldfire/pcm-coldfire.c
+++ b/firmware/target/coldfire/pcm-coldfire.c
@@ -294,8 +294,6 @@ void DMA0(void) __attribute__ ((interrupt_handler, section(".icode")));
 void DMA0(void)
 {
     unsigned long res = DSR0;
-    void *start;
-    size_t size;
 
     and_l(~(DMA_EEXT | DMA_INT), &DCR0); /* per request and int OFF */
     DSR0 = 1; /* Clear interrupt and errors */
@@ -311,17 +309,18 @@ void DMA0(void)
 #endif
     }
 
-    /* Force stop on error */
-    pcm_play_get_more_callback((res & 0x70) ? NULL : &start, &size);
+    const void *addr;
+    size_t size;
 
-    if (size != 0)
+    if (pcm_play_dma_complete_callback((res & 0x70) ?
+                                       PCM_DMAST_ERR_DMA : PCM_DMAST_OK,
+                                       &addr, &size))
     {
-        SAR0 = (unsigned long)start;     /* Source address */
-        BCR0 = size;                     /* Bytes to transfer */
+        SAR0 = (unsigned long)addr;      /* Source address */
+        BCR0 = (unsigned long)size;      /* Bytes to transfer */
         or_l(DMA_EEXT | DMA_INT, &DCR0); /* per request and int ON */
 
-        /* Call buffer callback */
-        pcm_play_dma_started_callback();
+        pcm_play_dma_status_callback(PCM_DMAST_STARTED);
     }
     /* else inished playing */
 } /* DMA0 */
@@ -368,7 +367,7 @@ void pcm_rec_unlock(void)
 
 void pcm_rec_dma_start(void *addr, size_t size)
 {
-    /* stop any DMA in progress */
+    /* Stop any DMA in progress */
     pcm_rec_dma_stop();
 
     and_l(~PDIR2_FIFO_RESET, &DATAINCONTROL);
@@ -430,16 +429,14 @@ void DMA1(void) __attribute__ ((interrupt_handler, section(".icode")));
 void DMA1(void)
 {
     unsigned long res = DSR1;
-    int status = 0;
-    void *start;
-    size_t size;
+    enum pcm_dma_status status = PCM_DMAST_OK;
 
     and_l(~(DMA_EEXT | DMA_INT), &DCR1); /* per request and int OFF */
     DSR1 = 1;                            /* Clear interrupt and errors */
 
     if (res & 0x70)
     {
-        status = DMA_REC_ERROR_DMA;
+        status = PCM_DMAST_ERR_DMA;
         logf("DMA1 err: %02x", res);
 #if 0
         logf("  SAR1: %08x", SAR1);
@@ -456,19 +453,22 @@ void DMA1(void)
          * Ignore valnogood since several sources don't set it properly. */
         /* clear: ebu1cnew, symbolerr, parityerr */
         INTERRUPTCLEAR = (1 << 25) | (1 << 23) | (1 << 22);
-        status = DMA_REC_ERROR_SPDIF;
+        status = PCM_DMAST_ERR_SPDIF;
         logf("spdif err");
     }
 #endif
 
     /* Inform PCM we have more data (or error) */
-    pcm_rec_more_ready_callback(status, &start, &size);
+    void *addr;
+    size_t size;
 
-    if (size != 0)
+    if (pcm_rec_dma_complete_callback(status, &addr, &size))
     {
-        DAR1 = (unsigned long)start;     /* Destination address */
+        DAR1 = (unsigned long)addr;      /* Destination address */
         BCR1 = (unsigned long)size;      /* Bytes to transfer */
         or_l(DMA_EEXT | DMA_INT, &DCR1); /* per request and int ON */
+
+        pcm_rec_dma_status_callback(PCM_DMAST_STARTED);
     }
 } /* DMA1 */
 
diff --git a/firmware/target/hosted/android/pcm-android.c b/firmware/target/hosted/android/pcm-android.c
index 4e58707d0a..7a0f28634e 100644
--- a/firmware/target/hosted/android/pcm-android.c
+++ b/firmware/target/hosted/android/pcm-android.c
@@ -80,8 +80,8 @@ Java_org_rockbox_RockboxPCM_nativeWrite(JNIEnv *env, jobject this,
 
     if (!pcm_data_size) /* get some initial data */
     {
-        new_buffer = true;
-        pcm_play_get_more_callback((void**) &pcm_data_start, &pcm_data_size);
+        new_buffer = pcm_play_dma_complete_callback(PCM_DMAST_OK,
+                        (const void**)&pcm_data_start, &pcm_data_size);
     }
 
     while(left > 0 && pcm_data_size)
@@ -99,7 +99,7 @@ Java_org_rockbox_RockboxPCM_nativeWrite(JNIEnv *env, jobject this,
         if (new_buffer)
         {
             new_buffer = false;
-            pcm_play_dma_started_callback();
+            pcm_play_dma_status_callback(PCM_DMAST_STARTED);
 
             /* NOTE: might need to release the mutex and sleep here if the
                buffer is shorter than the required buffer (like pcm-sdl.c) to
@@ -114,15 +114,15 @@ Java_org_rockbox_RockboxPCM_nativeWrite(JNIEnv *env, jobject this,
 
         if (pcm_data_size == 0) /* need new data */
         {
-            new_buffer = true;
-            pcm_play_get_more_callback((void**)&pcm_data_start, &pcm_data_size);
+            new_buffer = pcm_play_dma_complete_callback(PCM_DMAST_OK,
+                            (const void**)&pcm_data_start, &pcm_data_size);
         }
         else /* increment data pointer and feed more */
             pcm_data_start += transfer_size;
     }
 
-    if (new_buffer && pcm_data_size)
-        pcm_play_dma_started_callback();
+    if (new_buffer)
+        pcm_play_dma_status_callback(PCM_DMAST_STARTED);
 
     unlock_audio();
     return max_size - left;
@@ -154,7 +154,7 @@ void pcm_play_dma_start(const void *addr, size_t size)
 
 void pcm_play_dma_stop(void)
 {
-    /* NOTE: due to how pcm_play_get_more_callback() works, this is
+    /* NOTE: due to how pcm_play_dma_complete_callback() works, this is
      * possibly called from nativeWrite(), i.e. another (host) thread
      * => need to discover the appropriate JNIEnv* */
     JNIEnv* env = getJavaEnvironment();
diff --git a/firmware/target/hosted/maemo/pcm-gstreamer.c b/firmware/target/hosted/maemo/pcm-gstreamer.c
index e5620d0702..61f33cbadd 100644
--- a/firmware/target/hosted/maemo/pcm-gstreamer.c
+++ b/firmware/target/hosted/maemo/pcm-gstreamer.c
@@ -189,9 +189,8 @@ static void feed_data(GstElement * appsrc, guint size_hint, void *unused)
        from inside gstreamer's stream thread as it will deadlock */
     inside_feed_data = 1;
 
-    pcm_play_get_more_callback((void **)&pcm_data, &pcm_data_size);
-
-    if (pcm_data_size != 0)
+    if (pcm_play_dma_complete_callback(PCM_DMAST_OK, (const void **)&pcm_data,
+                                       &pcm_data_size))
     {
         GstBuffer *buffer = gst_buffer_new ();
         GstFlowReturn ret;
@@ -205,7 +204,7 @@ static void feed_data(GstElement * appsrc, guint size_hint, void *unused)
         if (ret != 0)
             DEBUGF("push-buffer error result: %d\n", ret);
 
-        pcm_play_dma_started_callback();
+        pcm_play_dma_status_callback(PCM_DMAST_STARTED);
     } else
     {
         DEBUGF("feed_data: No Data.\n");
diff --git a/firmware/target/hosted/pcm-alsa.c b/firmware/target/hosted/pcm-alsa.c
index b78993dd0a..1385f75b34 100644
--- a/firmware/target/hosted/pcm-alsa.c
+++ b/firmware/target/hosted/pcm-alsa.c
@@ -223,9 +223,11 @@ static bool fill_frames(void)
         if (!pcm_size)
         {
             new_buffer = true;
-            pcm_play_get_more_callback((void **)&pcm_data, &pcm_size);
-            if (!pcm_size || !pcm_data)
+            if (!pcm_play_dma_complete_callback(PCM_DMAST_OK,
+                    (const void **)&pcm_data, &pcm_size))
+            {
                 return false;
+            }
         }
         copy_n = MIN((ssize_t)pcm_size, frames_left*4);
         memcpy(&frames[2*(period_size-frames_left)], pcm_data, copy_n);
@@ -237,7 +239,7 @@ static bool fill_frames(void)
         if (new_buffer)
         {
             new_buffer = false;
-            pcm_play_dma_started_callback();
+            pcm_play_dma_status_callback(PCM_DMAST_STARTED);
         }
     }
     return true;
diff --git a/firmware/target/hosted/sdl/pcm-sdl.c b/firmware/target/hosted/sdl/pcm-sdl.c
index 020928d572..2c535b2dc5 100644
--- a/firmware/target/hosted/sdl/pcm-sdl.c
+++ b/firmware/target/hosted/sdl/pcm-sdl.c
@@ -56,7 +56,7 @@ static int sim_volume = 0;
 #if CONFIG_CODEC == SWCODEC
 static int cvt_status = -1;
 
-static Uint8* pcm_data;
+static const Uint8* pcm_data;
 static size_t pcm_data_size;
 static size_t pcm_sample_bytes;
 static size_t pcm_channel_bytes;
@@ -109,7 +109,7 @@ void pcm_play_dma_start(const void *addr, size_t size)
 {
     pcm_dma_apply_settings_nolock();
 
-    pcm_data = (Uint8 *) addr;
+    pcm_data = addr;
     pcm_data_size = size;
 
     SDL_PauseAudio(0);
@@ -245,48 +245,48 @@ static void sdl_audio_callback(struct pcm_udata *udata, Uint8 *stream, int len)
 
     /* Audio card wants more? Get some more then. */
     while (len > 0) {
-        new_buffer = true;
-        pcm_play_get_more_callback((void **)&pcm_data, &pcm_data_size);
+        new_buffer = pcm_play_dma_complete_callback(PCM_DMAST_OK,
+                        (const void **)&pcm_data, &pcm_data_size);
+
+        if (!new_buffer) {
+            DEBUGF("sdl_audio_callback: No Data.\n");
+            break;
+        }
+
     start:
-        if (pcm_data_size != 0) {
-            udata->num_in  = pcm_data_size / pcm_sample_bytes;
-            udata->num_out = len / pcm_sample_bytes;
+        udata->num_in  = pcm_data_size / pcm_sample_bytes;
+        udata->num_out = len / pcm_sample_bytes;
 
-            write_to_soundcard(udata);
+        write_to_soundcard(udata);
 
-            udata->num_in  *= pcm_sample_bytes;
-            udata->num_out *= pcm_sample_bytes;
+        udata->num_in  *= pcm_sample_bytes;
+        udata->num_out *= pcm_sample_bytes;
 
+        if (new_buffer)
+        {
+            new_buffer = false;
+            pcm_play_dma_status_callback(PCM_DMAST_STARTED);
 
-            if (new_buffer)
+            if ((size_t)len > udata->num_out)
             {
-                new_buffer = false;
-                pcm_play_dma_started_callback();
+                int delay = pcm_data_size*250 / pcm_sampr - 1;
 
-                if ((size_t)len > udata->num_out)
+                if (delay > 0)
                 {
-                    int delay = pcm_data_size*250 / pcm_sampr - 1;
-                
-                    if (delay > 0)
-                    {
-                        SDL_UnlockMutex(audio_lock);
-                        SDL_Delay(delay);
-                        SDL_LockMutex(audio_lock);
-
-                        if (!pcm_is_playing())
-                            break;
-                    }
+                    SDL_UnlockMutex(audio_lock);
+                    SDL_Delay(delay);
+                    SDL_LockMutex(audio_lock);
+
+                    if (!pcm_is_playing())
+                        break;
                 }
             }
-
-            pcm_data      += udata->num_in;
-            pcm_data_size -= udata->num_in;
-            udata->stream += udata->num_out;
-            len           -= udata->num_out;
-        } else {
-            DEBUGF("sdl_audio_callback: No Data.\n");
-            break;
         }
+
+        pcm_data      += udata->num_in;
+        pcm_data_size -= udata->num_in;
+        udata->stream += udata->num_out;
+        len           -= udata->num_out;
     }
 
     SDL_UnlockMutex(audio_lock);
diff --git a/firmware/target/mips/ingenic_jz47xx/pcm-jz4740.c b/firmware/target/mips/ingenic_jz47xx/pcm-jz4740.c
index 1ed413c9ae..83d3646ed1 100644
--- a/firmware/target/mips/ingenic_jz47xx/pcm-jz4740.c
+++ b/firmware/target/mips/ingenic_jz47xx/pcm-jz4740.c
@@ -63,7 +63,7 @@ void pcm_dma_apply_settings(void)
     audiohw_set_frequency(pcm_sampr);
 }
 
-static void* playback_address;
+static const void* playback_address;
 static inline void set_dma(const void *addr, size_t size)
 {
     int burst_size;
@@ -96,21 +96,19 @@ static inline void set_dma(const void *addr, size_t size)
     REG_DMAC_DRSR(DMA_AIC_TX_CHANNEL)  = DMAC_DRSR_RS_AICOUT;
     REG_DMAC_DCMD(DMA_AIC_TX_CHANNEL)  = (DMAC_DCMD_SAI | DMAC_DCMD_SWDH_32 | burst_size | DMAC_DCMD_DWDH_16 | DMAC_DCMD_TIE);
 
-    playback_address = (void*)addr;
+    playback_address = addr;
 }
 
 static inline void play_dma_callback(void)
 {
-    void *start;
+    const void *start;
     size_t size;
 
-    pcm_play_get_more_callback(&start, &size);
-
-    if (size != 0)
+    if (pcm_play_dma_complete_callback(PCM_DMAST_OK, &start, &size))
     {
         set_dma(start, size);
         REG_DMAC_DCCSR(DMA_AIC_TX_CHANNEL) |= DMAC_DCCSR_EN;
-        pcm_play_dma_started_callback();
+        pcm_play_dma_status_callback(PCM_DMAST_STARTED);
     }
 }