linux-kernel - Re: [PATCH 3/3] ASoC: fsl_asrc_dma: allocate memory from dma device

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Message-ID: <CAA+D8APbzGCSHOwGyBZjf1TYqo2K0s0dvoLjHS+FsT_RLGrb2w@mail.gmail.com>
Date: Thu, 29 Jan 2026 17:37:35 +0800
From: Shengjiu Wang <shengjiu.wang@...il.com>
To: Daniel Baluta <daniel.baluta@....nxp.com>
Cc: Shengjiu Wang <shengjiu.wang@....com>, lgirdwood@...il.com, broonie@...nel.org, 
	robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, shawnguo@...nel.org, 
	s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com, 
	linux-sound@...r.kernel.org, devicetree@...r.kernel.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Xiubo.Lee@...il.com, nicoleotsuka@...il.com, perex@...ex.cz, tiwai@...e.com, 
	linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 3/3] ASoC: fsl_asrc_dma: allocate memory from dma device

On Thu, Jan 29, 2026 at 5:22 PM Daniel Baluta <daniel.baluta@....nxp.com> wrote:
>
> On 1/28/26 09:18, Shengjiu Wang wrote:
> > As the dma device may support dma-coherent property on the i.MX952,
> > allocate memory from dma device to make asrc driver to be compatible with
> > such a case.
>
>
> This commit message refers to imx952 but the change in the code apply to all supported platforms
>
> So in not really clear what is the intention of it.

The dma-coherent property is used to indicate a device is capable of
coherent DMA operations.
Which is applied to the EDMA device on i.MX952,  in order to support
such EDMA device,
the memory is need to allocated from DMA device,

The code change is compatible for non dma-coherent and dma-coherent dma devices.

>
> Also, it is not clear why do you allocate a pair only to free it at the end of the function.

As the comment in the code says,  it is to get the dma device handler
for memory allocation
. After that, it is freed.

best regards
Shengjiu wang
>
>