[alsa-devel] [PATCHv2 16/20] ASoC: OMAP: Use DMA operating mode of McBSP

[Eduardo Valentin]

On Wed, Aug 12, 2009 at 02:38:38PM +0200, Jarkko Nikula wrote:
> On Tue, 11 Aug 2009 16:05:27 +0300
> Eduardo Valentin <eduardo.valentin at nokia.com> wrote:
> 
> > From: Eduardo Valentin <eduardo.valentin at nokia.com>
> > 
> > Signed-off-by: Eduardo Valentin <eduardo.valentin at nokia.com>
> > ---
> >  sound/soc/omap/omap-mcbsp.c |    8 ++++++--
> >  sound/soc/omap/omap-pcm.c   |   13 +++++++++++--
> >  sound/soc/omap/omap-pcm.h   |    1 +
> >  3 files changed, 18 insertions(+), 4 deletions(-)
> > 
> ...
> > diff --git a/sound/soc/omap/omap-pcm.c b/sound/soc/omap/omap-pcm.c
> > index 0c1ba0f..d8f52e8 100644
> > --- a/sound/soc/omap/omap-pcm.c
> > +++ b/sound/soc/omap/omap-pcm.c
> > @@ -144,7 +144,9 @@ static int omap_pcm_prepare(struct snd_pcm_substream *substream)
> >  
> >  	memset(&dma_params, 0, sizeof(dma_params));
> >  
> > -	if (cpu_is_omap34xx())
> > +	/* TODO: Currently, MODE_ELEMENT == MODE_FRAME */
> > +	if (cpu_is_omap34xx() &&
> > +			(dma_data->dma_op_mode == MCBSP_DMA_MODE_THRESHOLD))
> >  		sync_mode = OMAP_DMA_SYNC_FRAME;
> >  	else
> >  		sync_mode = OMAP_DMA_SYNC_ELEMENT;
> 
> Note, you could avoid the compile error if you move this into
> omap-mcbsp.c and pass only sync_mode here. Probably as easy as
> dma_data->sync_mode since OMAP_DMA_SYNC_ELEMENT is zero.

Yes, it is way better to use dma_data->sync_mode. Good point.

> 
> The McBSP DAI must and can know the DMA parameters (like sync_mode) but
> otherwise (like MCBSP_DMA_MODE_xxx) it sounds unnecessary glue between
> the drivers.


I think these MCBSP_DMA_MODE_xxx references can be moved to omap-mcbsp.c.
Will try it and send more comments.

> 
> > @@ -193,9 +195,16 @@ static int omap_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
> >  	struct omap_pcm_dma_data *dma_data = prtd->dma_data;
> >  	unsigned long flags;
> >  	int ret = 0;
> > -	int samples = snd_pcm_lib_period_bytes(substream) >> 1;
> > +	int samples;
> >  
> >  	spin_lock_irqsave(&prtd->lock, flags);
> > +
> > +	/* TODO: Currently, MODE_ELEMENT == MODE_FRAME */
> > +	if (dma_data->dma_op_mode == MCBSP_DMA_MODE_THRESHOLD)
> > +		samples = snd_pcm_lib_period_bytes(substream) >> 1;
> > +	else
> > +		samples = 1;
> > +
> 
> Can these lines in this patch and in patch 15 to be moved into
> omap_mcbsp_trigger? For me it looks it would simplify and remove the
> glue between the drivers.

These sample calculation can be moved to the .set_threshold I've
added. But I'm afraid we can not move this threshold thing to omap_mcbsp_dai_trigger.
At that point, DMA has been started by omap_pcm_trigger, this will generate
a DMA sync error at the begging of stream execution.

> 
> 
> -- 
> Jarkko

-- 
Eduardo Valentin
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