linux-kernel - Re: [PATCH v2 4/8] dmaengine: dw-edma: Pass dma_slave_config to dw_edma_device

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Message-ID: <bff84f52-a23c-4a76-977b-9deb2306b154@kernel.org>
Date: Fri, 19 Dec 2025 19:38:07 +0900
From: Damien Le Moal <dlemoal@...nel.org>
To: Frank Li <Frank.Li@....com>, Vinod Koul <vkoul@...nel.org>,
 Manivannan Sadhasivam <mani@...nel.org>,
 Krzysztof Wilczyński <kwilczynski@...nel.org>,
 Kishon Vijay Abraham I <kishon@...nel.org>,
 Bjorn Helgaas <bhelgaas@...gle.com>, Christoph Hellwig <hch@....de>,
 Sagi Grimberg <sagi@...mberg.me>, Chaitanya Kulkarni <kch@...dia.com>,
 Herbert Xu <herbert@...dor.apana.org.au>,
 "David S. Miller" <davem@...emloft.net>,
 Nicolas Ferre <nicolas.ferre@...rochip.com>,
 Alexandre Belloni <alexandre.belloni@...tlin.com>,
 Claudiu Beznea <claudiu.beznea@...on.dev>, Koichiro Den <den@...inux.co.jp>,
 Niklas Cassel <cassel@...nel.org>
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-pci@...r.kernel.org, linux-nvme@...ts.infradead.org,
 mhi@...ts.linux.dev, linux-arm-msm@...r.kernel.org,
 linux-crypto@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 imx@...ts.linux.dev
Subject: Re: [PATCH v2 4/8] dmaengine: dw-edma: Pass dma_slave_config to
 dw_edma_device_transfer()

On 12/19/25 00:56, Frank Li wrote:
> Pass dma_slave_config to dw_edma_device_transfer() to support atomic
> configuration and descriptor preparation when a non-NULL config is
> provided to device_prep_config_sg().
> 
> Tested-by: Niklas Cassel <cassel@...nel.org>
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
>  drivers/dma/dw-edma/dw-edma-core.c | 22 ++++++++++++++++------
>  1 file changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index e005b7bdaee156a3f4573b4734f50e3e47553dd2..1863254bf61eb892cb0cf8934e53b40d32027dfa 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -230,6 +230,15 @@ static int dw_edma_device_config(struct dma_chan *dchan,
>  	return 0;
>  }
>  
> +static struct dma_slave_config *
> +dw_edma_device_get_config(struct dma_chan *dchan,
> +			  struct dma_slave_config *config)
> +{
> +	struct dw_edma_chan *chan = dchan2dw_edma_chan(dchan);
> +
> +	return config ? config : &chan->config;
> +}

I would rewrite this as:

static struct dma_slave_config *
dw_edma_device_get_config(struct dma_chan *dchan,
			  struct dma_slave_config *config)
{
	struct dw_edma_chan *chan;

	if (config)
		return config;

	chan = dchan2dw_edma_chan(dchan);

	return &chan->config;
}

That avoids the call to dchan2dw_edma_chan() if config is specified.

-- 
Damien Le Moal
Western Digital Research