linux-kernel - Re: [PATCH] dmaengine: fsl-edma: fix channel parameter config for fixed channel requests

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Message-ID: <aMrI2ZEz6Zdoj6iy@lizhi-Precision-Tower-5810>
Date: Wed, 17 Sep 2025 10:42:33 -0400
From: Frank Li <Frank.li@....com>
To: Joy Zou <joy.zou@....com>
Cc: Vinod Koul <vkoul@...nel.org>, imx@...ts.linux.dev,
	dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] dmaengine: fsl-edma: fix channel parameter config for
 fixed channel requests

On Wed, Sep 17, 2025 at 05:53:42PM +0800, Joy Zou wrote:
> Configure only the requested channel when a fixed channel is specified
> to avoid modifying other channels unintentionally.
>
> Fix parameter configuration when a fixed DMA channel is requested on
> i.MX9 AON domain and i.MX8QM/QXP/DXL platforms. When a client requests
> a fixed channel (e.g., channel 6), the driver traverses channels 0-5
> and may unintentionally modify their configuration if they are unused.
>
> This leads to issues such as setting the `is_multi_fifo` flag unexpectedly,
> causing memcpy tests to fail when using the dmatest tool.
>
> Only affect edma memcpy test when the channel is fixed.
>
> Fixes: 72f5801a4e2b ("dmaengine: fsl-edma: integrate v3 support")
> Signed-off-by: Joy Zou <joy.zou@....com>
> Cc: stable@...r.kernel.org

Reviewed-by: Frank Li <Frank.Li@....com>

> ---
>  drivers/dma/fsl-edma-main.c | 26 +++++++++++---------------
>  1 file changed, 11 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/dma/fsl-edma-main.c b/drivers/dma/fsl-edma-main.c
> index 97583c7d51a2e8e7a50c7eb4f5ff0582ac95798d..f0c1a2a3fd26e663b3f0b918ff979a68af510fbf 100644
> --- a/drivers/dma/fsl-edma-main.c
> +++ b/drivers/dma/fsl-edma-main.c
> @@ -317,10 +317,8 @@ static struct dma_chan *fsl_edma3_xlate(struct of_phandle_args *dma_spec,
>  			return NULL;
>  		i = fsl_chan - fsl_edma->chans;
>
> -		fsl_chan->priority = dma_spec->args[1];
> -		fsl_chan->is_rxchan = dma_spec->args[2] & FSL_EDMA_RX;
> -		fsl_chan->is_remote = dma_spec->args[2] & FSL_EDMA_REMOTE;
> -		fsl_chan->is_multi_fifo = dma_spec->args[2] & FSL_EDMA_MULTI_FIFO;
> +		if (!b_chmux && i != dma_spec->args[0])
> +			continue;
>
>  		if ((dma_spec->args[2] & FSL_EDMA_EVEN_CH) && (i & 0x1))
>  			continue;
> @@ -328,17 +326,15 @@ static struct dma_chan *fsl_edma3_xlate(struct of_phandle_args *dma_spec,
>  		if ((dma_spec->args[2] & FSL_EDMA_ODD_CH) && !(i & 0x1))
>  			continue;
>
> -		if (!b_chmux && i == dma_spec->args[0]) {
> -			chan = dma_get_slave_channel(chan);
> -			chan->device->privatecnt++;
> -			return chan;
> -		} else if (b_chmux && !fsl_chan->srcid) {
> -			/* if controller support channel mux, choose a free channel */
> -			chan = dma_get_slave_channel(chan);
> -			chan->device->privatecnt++;
> -			fsl_chan->srcid = dma_spec->args[0];
> -			return chan;
> -		}
> +		fsl_chan->srcid = dma_spec->args[0];
> +		fsl_chan->priority = dma_spec->args[1];
> +		fsl_chan->is_rxchan = dma_spec->args[2] & FSL_EDMA_RX;
> +		fsl_chan->is_remote = dma_spec->args[2] & FSL_EDMA_REMOTE;
> +		fsl_chan->is_multi_fifo = dma_spec->args[2] & FSL_EDMA_MULTI_FIFO;
> +
> +		chan = dma_get_slave_channel(chan);
> +		chan->device->privatecnt++;
> +		return chan;
>  	}
>  	return NULL;
>  }
>
> ---
> base-commit: 05af764719214d6568adb55c8749dec295228da8
> change-id: 20250917-b4-edma-chanconf-da616503f29f
>
> Best regards,
> --
> Joy Zou <joy.zou@....com>
>