[alsa-devel] [PATCH 16/20] ASoC: OMAP: Use McBSP threshold again

[Jarkko Nikula]

On Thu, 30 Jul 2009 15:49:39 +0300
Eduardo Valentin <eduardo.valentin at nokia.com> wrote:

> Now this patch implements again the McBSP threshold
> usage for OMAP ASoC.
> 
> We figured out that there is no need to have so much
> SW control in order to have DMA in idle state during
> audio streaming. Configuring McBSP threshold value
> and DMA to FRAME_SYNC are sufficient.
> 
> Signed-off-by: Eduardo Valentin <eduardo.valentin at nokia.com>
> ---
>  sound/soc/omap/omap-pcm.c |   37 +++++++++++++++++++++++++++++++++++--
>  1 files changed, 35 insertions(+), 2 deletions(-)
> 
> @@ -192,6 +203,12 @@ static int omap_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
>  	case SNDRV_PCM_TRIGGER_RESUME:
>  	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
>  		prtd->period_index = 0;
> +		/* Configure McBSP internal buffer usage */
> +		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
> +			omap_mcbsp_set_tx_threshold(bus_id, samples - 1);
> +		else
> +			omap_mcbsp_set_rx_threshold(bus_id, samples - 1);
> +
>  		omap_start_dma(prtd->dma_ch);
>  		break;
>  
Oops, didn't notice this before. This will hard glue the DMA and McBSP
together. Even currently there is only McBSP based DAI link driver,
there can be others as well. EAC DAI for OMAP2420 would be necessary
for instance if one wants to develop ASoC support for Nokia N800. Nokia
N810 could use that too.


-- 
Jarkko
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