ASoC: OMAP: Enhance OMAP1510 DMA progress software counter

Enhance period_index accuracy, particularly just before buffer rewind, by
making use of DMA interrupt status flags in addition to simply counting up
interrupts.

Created against linux-2.6.31-rc5.

Tested on Amstrad Delta.

Signed-off-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Acked-by: Jarkko Nikula <jhnikula@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 20 insertions, 2 deletions

diff --git a/sound/soc/omap/omap-pcm.c b/sound/soc/omap/omap-pcm.c
index 3e3a9d478c0d..12e14c01068e 100644
--- a/sound/soc/omap/omap-pcm.c
+++ b/sound/soc/omap/omap-pcm.c
@@ -68,8 +68,21 @@ static void omap_pcm_dma_irq(int ch, u16 stat, void *data)
                  * that can be used by omap_pcm_pointer() instead.
                  */
                 spin_lock_irqsave(&prtd->lock, flags);
+                if ((stat == OMAP_DMA_LAST_IRQ) &&
+                                (prtd->period_index == runtime->periods - 1)) {
+                        /* we are in sync, do nothing */
+                        spin_unlock_irqrestore(&prtd->lock, flags);
+                        return;
+                }
                 if (prtd->period_index >= 0) {
-                        if (++prtd->period_index == runtime->periods) {
+                        if (stat & OMAP_DMA_BLOCK_IRQ) {
+                                /* end of buffer reached, loop back */
+                                prtd->period_index = 0;
+                        } else if (stat & OMAP_DMA_LAST_IRQ) {
+                                /* update the counter for the last period */
+                                prtd->period_index = runtime->periods - 1;
+                        } else if (++prtd->period_index >= runtime->periods) {
+                                /* end of buffer missed? loop back */
                                 prtd->period_index = 0;
                         }
                 }
@@ -175,7 +188,12 @@ static int omap_pcm_prepare(struct snd_pcm_substream *substream)
         dma_params.frame_count  = runtime->periods;
         omap_set_dma_params(prtd->dma_ch, &dma_params);
 
-        omap_enable_dma_irq(prtd->dma_ch, OMAP_DMA_FRAME_IRQ);
+        if ((cpu_is_omap1510()) &&
+                        (substream->stream == SNDRV_PCM_STREAM_PLAYBACK))
+                omap_enable_dma_irq(prtd->dma_ch, OMAP_DMA_FRAME_IRQ |
+                              OMAP_DMA_LAST_IRQ | OMAP_DMA_BLOCK_IRQ);
+        else
+                omap_enable_dma_irq(prtd->dma_ch, OMAP_DMA_FRAME_IRQ);
 
         return 0;
 }