Commit d56b6eb6 authored by Grant Likely's avatar Grant Likely Committed by Mark Brown
Browse files

ASoC/mpc5200: get rid of the appl_ptr tracking nonsense 



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: default avatarGrant Likely <grant.likely@secretlab.ca>
Acked-by: default avatarLiam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
parent 8f159d72

sound/soc/fsl/mpc5200_dma.c

+8 −44
Original line number Diff line number Diff line
@@ -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);

		else

			bcom_gen_bd_tx_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 {

			bcom_gen_bd_tx_reset(s->bcom_task);

			psc_dma_bcom_enqueue_tx(s);

		}



		bcom_enable(s->bcom_task);

		spin_unlock_irqrestore(&psc_dma->lock, flags);

sound/soc/fsl/mpc5200_dma.h

+0 −2
Original line number Diff line number Diff line
@@ -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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