On Tue, 11 Aug 2009 01:07:10 +0200
Janusz Krzysztofik <jkrzyszt@xxxxxxxxxxxx> wrote:
> Enhance period index accuracy, particularly just before buffer rewind, by
> making use of DMA interrupt status flags in addition to simply counting up
> interrupts.
>
> Corrections 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 <jkrzyszt@xxxxxxxxxxxx>
>
> ---
> --- linux-2.6.31-rc5/sound/soc/omap/omap-pcm.c.orig 2009-08-10 22:41:25.000000000 +0200
> +++ linux-2.6.31-rc5/sound/soc/omap/omap-pcm.c 2009-08-10 23:15:46.000000000 +0200
> @@ -68,13 +68,27 @@ 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;
> }
> }
> spin_unlock_irqrestore(&prtd->lock, flags);
> - }
> + } 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.
> snd_pcm_period_elapsed(substream);
> }
> @@ -175,7 +189,12 @@ 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);
Indent OMAP_DMA_LAST_IRQ with tab(s) and spaces to the same column
than OMAP_DMA_FRAME_IRQ. Looks nicer then. Should the
OMAP_DMA_BLOCK_IRQ to be set since it is handled in omap_pcm_dma_irq?
--
Jarkko
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