Re: [PATCH] mtd: rawnand: lpc32xx_mlc: fail DMA transfers on timeout

[Vladimir Zapolskiy <vz@kernel.org>]

On 6/25/26 03:33, Pengpeng Hou wrote:
> lpc32xx_xmit_dma() starts a DMA transfer and waits up to one second for
> its completion, but it ignores the wait result and returns success after
> unmapping the buffer.
> 
> A timed out read can therefore return success with incomplete data, and a
> timed out write can continue the NAND operation without proof that the DMA
> payload reached the controller.
> 
> Terminate the DMA channel on timeout, unmap the scatterlist through the
> existing cleanup path, and return -ETIMEDOUT to the NAND read/write
> callers.
> 
> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
> ---
>   drivers/mtd/nand/raw/lpc32xx_mlc.c | 12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/lpc32xx_mlc.c b/drivers/mtd/nand/raw/lpc32xx_mlc.c
> index 19b13ae53..8f6a89d9b 100644
> --- a/drivers/mtd/nand/raw/lpc32xx_mlc.c
> +++ b/drivers/mtd/nand/raw/lpc32xx_mlc.c
> @@ -396,6 +396,7 @@ static int lpc32xx_xmit_dma(struct mtd_info *mtd, void *mem, int len,
>   	struct lpc32xx_nand_host *host = nand_get_controller_data(chip);
>   	struct dma_async_tx_descriptor *desc;
>   	int flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
> +	unsigned long time_left;
>   	int res;
>   
>   	sg_init_one(&host->sgl, mem, len);
> @@ -410,6 +411,7 @@ static int lpc32xx_xmit_dma(struct mtd_info *mtd, void *mem, int len,
>   				       flags);
>   	if (!desc) {
>   		dev_err(mtd->dev.parent, "Failed to prepare slave sg\n");
> +		res = -ENXIO;
>   		goto out1;
>   	}
>   
> @@ -420,7 +422,13 @@ static int lpc32xx_xmit_dma(struct mtd_info *mtd, void *mem, int len,
>   	dmaengine_submit(desc);
>   	dma_async_issue_pending(host->dma_chan);
>   
> -	wait_for_completion_timeout(&host->comp_dma, msecs_to_jiffies(1000));
> +	time_left = wait_for_completion_timeout(&host->comp_dma,
> +						msecs_to_jiffies(1000));
> +	if (!time_left) {
> +		dmaengine_terminate_sync(host->dma_chan);
> +		res = -ETIMEDOUT;
> +		goto out1;
> +	}
>   
>   	dma_unmap_sg(host->dma_chan->device->dev, &host->sgl, 1,
>   		     DMA_BIDIRECTIONAL);
> @@ -428,7 +436,7 @@ static int lpc32xx_xmit_dma(struct mtd_info *mtd, void *mem, int len,
>   out1:
>   	dma_unmap_sg(host->dma_chan->device->dev, &host->sgl, 1,
>   		     DMA_BIDIRECTIONAL);
> -	return -ENXIO;
> +	return res;
>   }
>   
>   static int lpc32xx_read_page(struct nand_chip *chip, uint8_t *buf,

Thank you for the change.

Reviewed-by: Vladimir Zapolskiy <vz@kernel.org>

-- 
Best wishes,
Vladimir

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