Improvements to Audio DMA management

ports/atmel-samd/audio_dma.c

@@ -35,6 +35,8 @@
 #include "py/mpstate.h"
 #include "py/runtime.h"
 
+#if CIRCUITPY_AUDIOIO || CIRCUITPY_AUDIOBUSIO
+
 static audio_dma_t* audio_dma_state[AUDIO_DMA_CHANNEL_COUNT];
 
 // This cannot be in audio_dma_state because it's volatile.
@@ -50,6 +52,18 @@ uint8_t find_free_audio_dma_channel(void) {
     return channel;
 }
 
+void audio_dma_disable_channel(uint8_t channel) {
+    if (channel >= AUDIO_DMA_CHANNEL_COUNT)
+        return;
+    dma_disable_channel(channel);
+}
+
+void audio_dma_enable_channel(uint8_t channel) {
+    if (channel >= AUDIO_DMA_CHANNEL_COUNT)
+        return;
+    dma_enable_channel(channel);
+}
+
 void audio_dma_convert_signed(audio_dma_t* dma, uint8_t* buffer, uint32_t buffer_length,
                               uint8_t** output_buffer, uint32_t* output_buffer_length,
                               uint8_t* output_spacing) {
@@ -252,16 +266,19 @@ audio_dma_result audio_dma_setup_playback(audio_dma_t* dma,
     }
 
     dma_configure(dma_channel, dma_trigger_source, true);
-    dma_enable_channel(dma_channel);
+    audio_dma_enable_channel(dma_channel);
 
     return AUDIO_DMA_OK;
 }
 
 void audio_dma_stop(audio_dma_t* dma) {
-    dma_disable_channel(dma->dma_channel);
-    disable_event_channel(dma->event_channel);
-    MP_STATE_PORT(playing_audio)[dma->dma_channel] = NULL;
-
+    uint8_t channel = dma->dma_channel;
+    if (channel < AUDIO_DMA_CHANNEL_COUNT) {
+        audio_dma_disable_channel(channel);
+        disable_event_channel(dma->event_channel);
+        MP_STATE_PORT(playing_audio)[channel] = NULL;
+        audio_dma_state[channel] = NULL;
+    }
     dma->dma_channel = AUDIO_DMA_CHANNEL_COUNT;
 }
 
@@ -290,7 +307,7 @@ void audio_dma_reset(void) {
     for (uint8_t i = 0; i < AUDIO_DMA_CHANNEL_COUNT; i++) {
         audio_dma_state[i] = NULL;
         audio_dma_pending[i] = false;
-        dma_disable_channel(i);
+        audio_dma_disable_channel(i);
         dma_descriptor(i)->BTCTRL.bit.VALID = false;
         MP_STATE_PORT(playing_audio)[i] = NULL;
     }
@@ -333,3 +350,4 @@ void audio_dma_background(void) {
         audio_dma_pending[i] = false;
     }
 }
+#endif

ports/atmel-samd/audio_dma.h

@@ -83,6 +83,9 @@ audio_dma_result audio_dma_setup_playback(audio_dma_t* dma,
                                           bool output_signed,
                                           uint32_t output_register_address,
                                           uint8_t dma_trigger_source);
+
+void audio_dma_disable_channel(uint8_t channel);
+void audio_dma_enable_channel(uint8_t channel);
 void audio_dma_stop(audio_dma_t* dma);
 bool audio_dma_get_playing(audio_dma_t* dma);
 void audio_dma_pause(audio_dma_t* dma);

ports/atmel-samd/background.c

@@ -56,7 +56,7 @@ void run_background_tasks(void) {
     assert_heap_ok();
     running_background_tasks = true;
 
-    #if (defined(SAMD21) && defined(PIN_PA02)) || defined(SAMD51)
+    #if CIRCUITPY_AUDIOIO || CIRCUITPY_AUDIOBUSIO
     audio_dma_background();
     #endif
     #if CIRCUITPY_DISPLAYIO

ports/atmel-samd/common-hal/audiobusio/PDMIn.c

@@ -385,7 +385,7 @@ uint32_t common_hal_audiobusio_pdmin_record_to_buffer(audiobusio_pdmin_obj_t* se
     init_event_channel_interrupt(event_channel, CORE_GCLK, EVSYS_ID_GEN_DMAC_CH_0 + dma_channel);
     // Turn on serializer now to get it in sync with DMA.
     i2s_set_serializer_enable(self->serializer, true);
-    dma_enable_channel(dma_channel);
+    audio_dma_enable_channel(dma_channel);
 
     // Record
     uint32_t buffers_processed = 0;
@@ -466,7 +466,7 @@ uint32_t common_hal_audiobusio_pdmin_record_to_buffer(audiobusio_pdmin_obj_t* se
     }
 
     disable_event_channel(event_channel);
-    dma_disable_channel(dma_channel);
+    audio_dma_disable_channel(dma_channel);
     // Turn off serializer, but leave clock on, to avoid mic startup delay.
     i2s_set_serializer_enable(self->serializer, false);