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Merged
merged 1 commit into from
Apr 30, 2025
Merged

Tweak audio playback on RP2 #10299

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63 changes: 38 additions & 25 deletions ports/raspberrypi/audio_dma.c
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Original file line number Diff line number Diff line change
Expand Up @@ -165,7 +165,9 @@ static void audio_dma_load_next_block(audio_dma_t *dma, size_t buffer_idx) {
}
}
// Enable the channel so that it can be played.
dma_hw->ch[dma_channel].al1_ctrl |= DMA_CH1_CTRL_TRIG_EN_BITS;
if (!dma->paused) {
dma_hw->ch[dma_channel].al1_ctrl |= DMA_CH1_CTRL_TRIG_EN_BITS;
}
dma->dma_result = AUDIO_DMA_OK;
}

Expand Down Expand Up @@ -301,6 +303,8 @@ audio_dma_result audio_dma_setup_playback(
MP_STATE_PORT(playing_audio)[dma->channel[0]] = dma;
MP_STATE_PORT(playing_audio)[dma->channel[1]] = dma;

dma->paused = false;

// Load the first two blocks up front.
audio_dma_load_next_block(dma, 0);
if (dma->dma_result != AUDIO_DMA_OK) {
Expand Down Expand Up @@ -331,6 +335,8 @@ audio_dma_result audio_dma_setup_playback(
1, // transaction count
false); // trigger
} else {
// Clear any latent interrupts so that we don't immediately disable channels.
dma_hw->ints0 |= (1 << dma->channel[0]) | (1 << dma->channel[1]);
// Enable our DMA channels on DMA_IRQ_0 to the CPU. This will wake us up when
// we're WFI.
dma_hw->inte0 |= (1 << dma->channel[0]) | (1 << dma->channel[1]);
Expand All @@ -344,6 +350,8 @@ audio_dma_result audio_dma_setup_playback(
}

void audio_dma_stop(audio_dma_t *dma) {
dma->paused = true;

// Disable our interrupts.
uint32_t channel_mask = 0;
if (dma->channel[0] < NUM_DMA_CHANNELS) {
Expand All @@ -363,12 +371,13 @@ void audio_dma_stop(audio_dma_t *dma) {

for (size_t i = 0; i < 2; i++) {
size_t channel = dma->channel[i];
dma->channel[i] = NUM_DMA_CHANNELS;
if (channel == NUM_DMA_CHANNELS) {
// Channel not in use.
continue;
}

dma_channel_config c = dma_channel_get_default_config(dma->channel[i]);
dma_channel_config c = dma_channel_get_default_config(channel);
channel_config_set_enable(&c, false);
dma_channel_set_config(channel, &c, false /* trigger */);

Expand All @@ -381,7 +390,6 @@ void audio_dma_stop(audio_dma_t *dma) {
dma_channel_set_trans_count(channel, 0, false /* trigger */);
dma_channel_unclaim(channel);
MP_STATE_PORT(playing_audio)[channel] = NULL;
dma->channel[i] = NUM_DMA_CHANNELS;
}
dma->playing_in_progress = false;

Expand All @@ -393,6 +401,7 @@ void audio_dma_stop(audio_dma_t *dma) {
void audio_dma_pause(audio_dma_t *dma) {
dma_hw->ch[dma->channel[0]].al1_ctrl &= ~DMA_CH0_CTRL_TRIG_EN_BITS;
dma_hw->ch[dma->channel[1]].al1_ctrl &= ~DMA_CH1_CTRL_TRIG_EN_BITS;
dma->paused = true;
}

void audio_dma_resume(audio_dma_t *dma) {
Expand All @@ -405,15 +414,14 @@ void audio_dma_resume(audio_dma_t *dma) {
dma_hw->ch[dma->channel[0]].al1_ctrl |= DMA_CH0_CTRL_TRIG_EN_BITS;
dma_hw->ch[dma->channel[1]].al1_ctrl |= DMA_CH1_CTRL_TRIG_EN_BITS;
}
dma->paused = false;
}

bool audio_dma_get_paused(audio_dma_t *dma) {
if (dma->channel[0] >= NUM_DMA_CHANNELS) {
return false;
}
uint32_t control = dma_hw->ch[dma->channel[0]].ctrl_trig;

return (control & DMA_CH0_CTRL_TRIG_EN_BITS) == 0;
return dma->playing_in_progress && dma->paused;
}

uint32_t audio_dma_pause_all(void) {
Expand Down Expand Up @@ -446,6 +454,9 @@ void audio_dma_init(audio_dma_t *dma) {

dma->channel[0] = NUM_DMA_CHANNELS;
dma->channel[1] = NUM_DMA_CHANNELS;

dma->playing_in_progress = false;
dma->paused = false;
}

void audio_dma_deinit(audio_dma_t *dma) {
Expand Down Expand Up @@ -486,37 +497,38 @@ bool audio_dma_get_playing(audio_dma_t *dma) {
// NOTE(dhalbert): I successfully printed from here while debugging.
// So it's possible, but be careful.
static void dma_callback_fun(void *arg) {
// Any audio interrupts that happen below will requeue the background task
// after updating channels_to_load_mask.
audio_dma_t *dma = arg;
if (dma == NULL) {
return;
}

common_hal_mcu_disable_interrupts();
uint32_t channels_to_load_mask = dma->channels_to_load_mask;
// This can be 0 if the background task was queued between the call to
// dma_callback_fun and the above read of channels_to_load_mask.
dma->channels_to_load_mask = 0;
common_hal_mcu_enable_interrupts();

// Load the blocks for the requested channels.
uint32_t channel = 0;
uint8_t first_filled_channel = NUM_DMA_CHANNELS;
size_t filled_count = 0;
while (channels_to_load_mask) {
if (channels_to_load_mask & 1) {
if (dma->channel[0] == channel) {
audio_dma_load_next_block(dma, 0);
filled_count++;
}
if (dma->channel[1] == channel) {
audio_dma_load_next_block(dma, 1);
filled_count++;
}
}
channels_to_load_mask >>= 1;
channel++;
if (dma->channel[0] != NUM_DMA_CHANNELS && (channels_to_load_mask & (1 << dma->channel[0]))) {
audio_dma_load_next_block(dma, 0);
first_filled_channel = dma->channel[0];
filled_count++;
}
// If we had to fill both buffers, then we missed the trigger from the other
// buffer. So restart the DMA.
if (filled_count == 2) {
dma_channel_start(dma->channel[0]);
if (dma->channel[1] != NUM_DMA_CHANNELS && (channels_to_load_mask & (1 << dma->channel[1]))) {
audio_dma_load_next_block(dma, 1);
first_filled_channel = dma->channel[1];
filled_count++;
}

// Restart if the other channel has been queued while we were filling the first or we filled two
// now. (Two get filled if the second buffer completes while the first is waiting in the
// background task queue.)
if (first_filled_channel != NUM_DMA_CHANNELS && (dma->channels_to_load_mask != 0 || filled_count == 2)) {
dma_channel_start(first_filled_channel);
}
}

Expand All @@ -537,6 +549,7 @@ void __not_in_flash_func(isr_dma_0)(void) {
dma->channels_to_load_mask |= mask;
// Disable the channel so that we don't play it without filling it.
dma_hw->ch[i].al1_ctrl &= ~DMA_CH0_CTRL_TRIG_EN_BITS;
// This is a noop if the callback is already queued.
background_callback_add(&dma->callback, dma_callback_fun, (void *)dma);
}
if (MP_STATE_PORT(background_pio_read)[i] != NULL) {
Expand Down
1 change: 1 addition & 0 deletions ports/raspberrypi/audio_dma.h
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@ typedef struct {
bool unsigned_to_signed;
bool output_signed;
bool playing_in_progress;
bool paused;
bool swap_channel;
} audio_dma_t;

Expand Down
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