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: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 8 insertions, 44 deletions

diff --git a/sound/soc/fsl/mpc5200_dma.c b/sound/soc/fsl/mpc5200_dma.c
index 986d3c8ab6e1..4e475861f5db 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);