[alsa-devel] [PATCH 2/4] ASoC: mmp: add audio dma support

[zhangfei gao]

On Tue, May 29, 2012 at 3:33 PM, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
> On Tue, May 29, 2012 at 10:48:54AM +0530, Vinod Koul wrote:
>> On Tue, 2012-05-29 at 13:14 +0800, zhangfei gao wrote:
>> >
>> > When debugging with putting snd_dmaengine_pcm_open to probe or
>> > pcm_new, there is issue.
>> > snd_dmaengine_pcm_open ->
>> > snd_pcm_hw_constraint_integer(substream->runtime,
>> >
>> > SNDRV_PCM_HW_PARAM_PERIODS);
>> > The runtime is only exist at runtime.
>> > So if using soc-dmaengine, I am afraid the snd_dmaengine_pcm_open has
>> > to be put in open instead of probe.
>> I think you got it wrong, the snd_dmaengine_pcm_open needs to be called
>> from your CPU pcm_open. See other examples how this is used in other
>> drivers.
>
> But, as I pointed out earlier, there's the issue of using the wrong
> struct device to allocate memory for the DMA engine.  That's something
> that my soc-dmaengine.c got _right_, and soc-dmaengine-pcm.c gets _wrong_.

Could you help clarify what's the struct device should be used?
Any example, not find soc-dmaengine.c.
When debug,
rtd->card->snd_card->dev is same as substream->pcm->card->dev, which
we using now.

Thanks a lot.