linux-kernel - Re: [PATCH] dmaengine: xilinx_dma: Reset DMA channel in dma_terminate

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Date:   Tue, 10 Dec 2019 11:31:13 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
Cc:     dan.j.williams@...el.com, michal.simek@...inx.com,
        nick.graumann@...il.com, andrea.merello@...il.com,
        appana.durga.rao@...inx.com, mcgrof@...nel.org,
        dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        git@...inx.com
Subject: Re: [PATCH] dmaengine: xilinx_dma: Reset DMA channel in
 dma_terminate_all

On 25-11-19, 12:12, Radhey Shyam Pandey wrote:
> Reset DMA channel after stop to ensure that pending transfers and FIFOs
> in the datapath are flushed or completed. It fixes intermittent data
> verification failure reported by xilinx dma test client.
> 
> Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
> ---
>  drivers/dma/xilinx/xilinx_dma.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
> index a9c5d5c..6f1539c 100644
> --- a/drivers/dma/xilinx/xilinx_dma.c
> +++ b/drivers/dma/xilinx/xilinx_dma.c
> @@ -2404,16 +2404,17 @@ static int xilinx_dma_terminate_all(struct dma_chan *dchan)
>  	u32 reg;
>  	int err;
>  
> -	if (chan->cyclic)
> -		xilinx_dma_chan_reset(chan);

So reset is required for non cyclic cases as well now?

> -
> -	err = chan->stop_transfer(chan);
> -	if (err) {
> -		dev_err(chan->dev, "Cannot stop channel %p: %x\n",
> -			chan, dma_ctrl_read(chan, XILINX_DMA_REG_DMASR));
> -		chan->err = true;
> +	if (!chan->cyclic) {
> +		err = chan->stop_transfer(chan);

no stop for cyclic now..?

> +		if (err) {
> +			dev_err(chan->dev, "Cannot stop channel %p: %x\n",
> +				chan, dma_ctrl_read(chan,
> +				XILINX_DMA_REG_DMASR));
> +			chan->err = true;
> +		}
>  	}
>  
> +	xilinx_dma_chan_reset(chan);
>  	/* Remove and free all of the descriptors in the lists */
>  	xilinx_dma_free_descriptors(chan);
>  	chan->idle = true;
> -- 
> 2.7.4

-- 
~Vinod