[alsa-devel] [RFC 7/7] ASoC: ep93xx-pcm: Use dmaengine PCM helper functions

[Lars-Peter Clausen]

On 02/27/2012 08:01 PM, Mika Westerberg wrote:
> On Mon, Feb 27, 2012 at 09:51:57AM +0100, Lars-Peter Clausen wrote:
>> On 02/27/2012 09:19 AM, Mika Westerberg wrote:
>>> On Wed, Feb 22, 2012 at 10:49:11AM +0100, Lars-Peter Clausen wrote:
>>>> Signed-off-by: Lars-Peter Clausen <lars at metafoo.de>
>>>
>>> For some reason, this doesn't work on my ep93xx based Sim.One board. On
>>> playback with mpg123 when I press stop, it continues to play whatever was on
>>> the ring-buffer forever. Without the patches it works fine.
>>>
>>> I'll try to find some time to debug this further.
>>
>> Hm, that’s interesting. The original ep93xx pcm driver was almost identical
>> to what the common helper functions do. The only difference I can spot right
>> now is, that it doesn't call dma_issue_pending after submitting the
>> descriptor. Could you try to comment out the dma_issue_pending in
>> soc-dmaengine-pcm.c and test whether it makes a difference?
> 
> I did try that but there was no effect, unfortunately.
> 
> However, I noticed that prtd->pos was never set to zero as it was in the
> original ep93xx-pcm driver. With following addition to your patch, playback
> works fine.
> 

Ah, nice :)

Thanks,
- Lars

> diff --git a/sound/soc/soc-dmaengine-pcm.c b/sound/soc/soc-dmaengine-pcm.c
> index 0526cf8..4420b70 100644
> --- a/sound/soc/soc-dmaengine-pcm.c
> +++ b/sound/soc/soc-dmaengine-pcm.c
> @@ -142,6 +142,7 @@ static int dmaengine_pcm_prepare_and_submit(struct snd_pcm_substream *substream)
>  
>  	direction = snd_pcm_substream_to_dma_direction(substream);
>  
> +	prtd->pos = 0;
>  	desc = chan->device->device_prep_dma_cyclic(chan,
>  		substream->runtime->dma_addr,
>  		snd_pcm_lib_buffer_bytes(substream),
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