[RFC PATCH v3 4/4] ASoC: fsl_asrc_dma: Fix data copying speed issue with EDMA

[Nicolin Chen]

On Fri, Jun 12, 2020 at 03:37:51PM +0800, Shengjiu Wang wrote:
> With EDMA, there is two dma channels can be used for dev_to_dev,
> one is from ASRC, one is from another peripheral (ESAI or SAI).
> 
> If we select the dma channel of ASRC, there is an issue for ideal
> ratio case, the speed of copy data is faster than sample
> frequency, because ASRC output data is very fast in ideal ratio
> mode.
> 
> So it is reasonable to use the dma channel of Back-End peripheral.
> then copying speed of DMA is controlled by data consumption
> speed in the peripheral FIFO,
> 
> Signed-off-by: Shengjiu Wang <shengjiu.wang at nxp.com>

Reviewed-by: Nicolin Chen <nicoleotsuka at gmail.com>