Enhance period_index accuracy, particularly just before buffer rewind, by
making use of DMA interrupt status flags in addition to simply counting up
interrupts.
Changes since v2:
> > > - }
> > > + } else if (stat == OMAP_DMA_LAST_IRQ)
> > > + return;
> >
> > Is this test needed? This interrupt is set only for playback on
> > omap1510 so this looks null-op.
>
> You're right, I have put it here before limiting the flag request to
> playback on OMAP1510 only. So it can be omitted...
> > > + omap_enable_dma_irq(prtd->dma_ch, OMAP_DMA_FRAME_IRQ |
> > > + OMAP_DMA_LAST_IRQ);
> >
> > Indent OMAP_DMA_LAST_IRQ with tab(s) and spaces to the same column
> > than OMAP_DMA_FRAME_IRQ. Looks nicer then.
>
> OK, will fix it.
>
> > Should the
> > OMAP_DMA_BLOCK_IRQ to be set since it is handled in omap_pcm_dma_irq?
>
> This one is already requested from inside omap_request_dma() and used
> inside omap1_dma_handle_ch() in addition to passing it to us.
But for less confusion, it'll be better if requested from here too.
Changes since v1:
1. Fix buggy DMA interrupt handling in case of multiple status flags set in
parallel.
2. Enable OMAP_DMA_LAST_IRQ only for playback on OMAP1510.
This patch applies on top of patch 2 from this series:
[RFC][PATCH 2/3] ASoC: OMAP: Make use of DMA channel self linking on OMAP1510
Created against linux-2.6.31-rc5.
Tested on Amstrad Delta.
Signed-off-by: Janusz Krzysztofik <jkrzy...@tis.icnet.pl>
---
--- linux-2.6.31-rc5/sound/soc/omap/omap-pcm.c.orig 2009-08-11
21:13:22.000000000 +0200
+++ linux-2.6.31-rc5/sound/soc/omap/omap-pcm.c 2009-08-11 21:34:34.000000000
+0200
@@ -68,8 +68,21 @@ static void omap_pcm_dma_irq(int ch, u16
* 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_p
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;
}
--
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