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

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Message-ID: <20200612081000.GD22422@Asurada-Nvidia>
Date:   Fri, 12 Jun 2020 01:10:00 -0700
From:   Nicolin Chen <nicoleotsuka@...il.com>
To:     Shengjiu Wang <shengjiu.wang@....com>
Cc:     lars@...afoo.de, perex@...ex.cz, tiwai@...e.com,
        lgirdwood@...il.com, broonie@...nel.org, timur@...nel.org,
        Xiubo.Lee@...il.com, festevam@...il.com,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [RFC PATCH v3 4/4] ASoC: fsl_asrc_dma: Fix data copying speed
 issue with EDMA

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@....com>

Reviewed-by: Nicolin Chen <nicoleotsuka@...il.com>