Sound drivers PCM DMA is supposed to free-run until told to stop
by the trigger callback. The current code tries to track appl_ptr,
to avoid stale buffer data getting played out at the end of the
data stream. Unfortunately it also results in race conditions
which can cause the audio to stall.
Signed-off-by: Grant Likely <grant.lik...@secretlab.ca>
---
sound/soc/fsl/mpc5200_dma.c | 52 +++++++------------------------------------
sound/soc/fsl/mpc5200_dma.h | 2 --
2 files changed, 8 insertions(+), 46 deletions(-)
diff --git a/sound/soc/fsl/mpc5200_dma.c b/sound/soc/fsl/mpc5200_dma.c
index 986d3c8..4e47586 100644
--- a/sound/soc/fsl/mpc5200_dma.c
+++ b/sound/soc/fsl/mpc5200_dma.c
@@ -65,36 +65,6 @@ static void psc_dma_bcom_enqueue_next_buffer(struct
psc_dma_stream *s)
s->period_next = (s->period_next + 1) % s->runtime->periods;
}
-static void psc_dma_bcom_enqueue_tx(struct psc_dma_stream *s)
-{
- if (s->appl_ptr > s->runtime->control->appl_ptr) {
- /*
- * In this case s->runtime->control->appl_ptr has wrapped
around.
- * Play the data to the end of the boundary, then wrap our own
- * appl_ptr back around.
- */
- while (s->appl_ptr < s->runtime->boundary) {
- if (bcom_queue_full(s->bcom_task))
- return;
-
- s->appl_ptr += s->runtime->period_size;
-
- psc_dma_bcom_enqueue_next_buffer(s);
- }
- s->appl_ptr -= s->runtime->boundary;
- }
-
- while (s->appl_ptr < s->runtime->control->appl_ptr) {
-
- if (bcom_queue_full(s->bcom_task))
- return;
-
- s->appl_ptr += s->runtime->period_size;
-
- psc_dma_bcom_enqueue_next_buffer(s);
- }
-}
-
/* Bestcomm DMA irq handler */
static irqreturn_t psc_dma_bcom_irq_tx(int irq, void *_psc_dma_stream)
{
@@ -107,8 +77,9 @@ static irqreturn_t psc_dma_bcom_irq_tx(int irq, void
*_psc_dma_stream)
bcom_retrieve_buffer(s->bcom_task, NULL, NULL);
s->period_current = (s->period_current+1) % s->runtime->periods;
+
+ psc_dma_bcom_enqueue_next_buffer(s);
}
- psc_dma_bcom_enqueue_tx(s);
spin_unlock(&s->psc_dma->lock);
/* If the stream is active, then also inform the PCM middle layer
@@ -182,28 +153,21 @@ static int psc_dma_trigger(struct snd_pcm_substream
*substream, int cmd)
s->period_next = 0;
s->period_current = 0;
s->active = 1;
-
- /* track appl_ptr so that we have a better chance of detecting
- * end of stream and not over running it.
- */
s->runtime = runtime;
- s->appl_ptr = s->runtime->control->appl_ptr -
- (runtime->period_size * runtime->periods);
/* Fill up the bestcomm bd queue and enable DMA.
* This will begin filling the PSC's fifo.
*/
spin_lock_irqsave(&psc_dma->lock, flags);
- if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE) {
+ if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE)
bcom_gen_bd_rx_reset(s->bcom_task);
- for (i = 0; i < runtime->periods; i++)
- if (!bcom_queue_full(s->bcom_task))
- psc_dma_bcom_enqueue_next_buffer(s);
- } else {
+ else
bcom_gen_bd_tx_reset(s->bcom_task);
- psc_dma_bcom_enqueue_tx(s);
- }
+
+ for (i = 0; i < runtime->periods; i++)
+ if (!bcom_queue_full(s->bcom_task))
+ psc_dma_bcom_enqueue_next_buffer(s);
bcom_enable(s->bcom_task);
spin_unlock_irqrestore(&psc_dma->lock, flags);
diff --git a/sound/soc/fsl/mpc5200_dma.h b/sound/soc/fsl/mpc5200_dma.h
index 529f7a0..d9c741b 100644
--- a/sound/soc/fsl/mpc5200_dma.h
+++ b/sound/soc/fsl/mpc5200_dma.h
@@ -19,8 +19,6 @@
*/
struct psc_dma_stream {
struct snd_pcm_runtime *runtime;
- snd_pcm_uframes_t appl_ptr;
-
int active;
struct psc_dma *psc_dma;
struct bcom_task *bcom_task;
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