ASoC: MPC5200: Support for buffer wrap around

The code in psc_dma_bcom_enqueue_tx() didn't account for the fact that
s->runtime->control->appl_ptr can wrap around to the beginning of the
buffer. This change fixes this problem.

Signed-off-by: John Bonesio <bones@secretlab.ca>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/sound/soc/fsl/mpc5200_dma.c b/sound/soc/fsl/mpc5200_dma.c
index f0a2d4071998..9ff62e3a9b1d 100644
--- a/sound/soc/fsl/mpc5200_dma.c
+++ b/sound/soc/fsl/mpc5200_dma.c
@@ -69,6 +69,23 @@ static void psc_dma_bcom_enqueue_next_buffer(struct psc_dma_stream *s)
 
 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->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))