[alsa-devel] [PATCH] ASoC: OMAP: Add checking to detect bufferless pcms
jy0922.shim at samsung.com
Wed Apr 22 11:48:00 CEST 2009
On 4/22/2009 5:30 PM, Jarkko Nikula wrote:
> On Wed, Apr 22, 2009 at 4:56 AM, Joonyoung Shim <jy0922.shim at samsung.com
> <mailto:jy0922.shim at samsung.com>> wrote:
> Add checking in hw_params and prepare to detect bufferless pcms(i.e. BT
> <--> codec).
> Signed-off-by: Joonyoung Shim <jy0922.shim at samsung.com
> <mailto:jy0922.shim at samsung.com>>
> 쟳ound/soc/omap/omap-pcm.c | 9 ++++++++-
> 1 files changed, 8 insertions(+), 1 deletions(-)
> diff --git a/sound/soc/omap/omap-pcm.c b/sound/soc/omap/omap-pcm.c
> index 07cf7f4..6454e15 100644
> --- a/sound/soc/omap/omap-pcm.c
> +++ b/sound/soc/omap/omap-pcm.c
> @@ -87,8 +87,10 @@ static int omap_pcm_hw_params(struct
> snd_pcm_substream *substream,
> 쟳truct omap_pcm_dma_data *dma_data = rtd->dai->cpu_dai->dma_data;
> 쟧nt err = 0;
> + /* return if this is a bufferless transfer e.g.
> + * codec <--> BT codec or GSM modem -- lg FIXME */
> 쟧f (!dma_data)
> - return -ENODEV;
> + return 0;
> I see exactly similar lines in s3c24xx-pcm.c but don't point now the use
> case where this is used and I don't have idea what is this all about.
> Is this something where DAI driver or another end of connection is used
> to provide clocking and the whole setup is then controlled with ALSA PCM
> API? Somehow I have the feeling that would there be a better way to
> achieve it than with dummy bufferless transfer?
I tested this patch with the omap3 target having the twl4030 codec. The
twl4030 codec driver supports the voice DAI to transfer pcm data between
modem and codec, and i added for test the dummy voice DAI in machine
driver. To transfer pcm data at modem <--> codec doesn't need DMA.
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