linux-kernel - Re: [PATCH v3] dmaengine: Add support for MEMCPY for imx-dma.

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Date:	Mon, 06 Feb 2012 17:08:14 +0530
From:	Vinod Koul <vinod.koul@...el.com>
To:	Javier Martin <javier.martin@...ta-silicon.com>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	dan.j.williams@...el.com, s.hauer@...gutronix.de
Subject: Re: [PATCH v3] dmaengine: Add support for MEMCPY for imx-dma.

On Tue, 2012-01-31 at 11:47 +0100, Javier Martin wrote:
> MEMCPY transfers allow DMA copies from memory to
> memory. This patch has been tested with dmatest
> device driver.
> 
> Signed-off-by: Javier Martin <javier.martin@...ta-silicon.com>
> ---
>  drivers/dma/imx-dma.c |   36 +++++++++++++++++++++++++++++++++++-
>  1 files changed, 35 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/dma/imx-dma.c b/drivers/dma/imx-dma.c
> index 3296a73..9aa6e85 100644
> --- a/drivers/dma/imx-dma.c
> +++ b/drivers/dma/imx-dma.c
> @@ -196,7 +196,8 @@ static int imxdma_alloc_chan_resources(struct dma_chan *chan)
>  	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
>  	struct imx_dma_data *data = chan->private;
>  
> -	imxdmac->dma_request = data->dma_request;
> +	if (data != NULL)
> +		imxdmac->dma_request = data->dma_request;
if you support memcopy then why should it _always_ require private
pointer?
>  
>  	dma_async_tx_descriptor_init(&imxdmac->desc, chan);
>  	imxdmac->desc.tx_submit = imxdma_tx_submit;
> @@ -328,6 +329,36 @@ static struct dma_async_tx_descriptor *imxdma_prep_dma_cyclic(
>  	return &imxdmac->desc;
>  }
>  
> +static struct dma_async_tx_descriptor *imxdma_prep_dma_memcpy(
> +	struct dma_chan *chan, dma_addr_t dest,
> +	dma_addr_t src, size_t len, unsigned long flags)
> +{
> +	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
> +	struct imxdma_engine *imxdma = imxdmac->imxdma;
> +	int ret;
> +
> +	dev_dbg(imxdma->dev, "%s channel: %d src=0x%x dst=0x%x len=%d\n",
> +			__func__, imxdmac->channel, src, dest, len);
> +
> +	if (imxdmac->status == DMA_IN_PROGRESS)
> +		return NULL;
thats not right, you should be able to prepare descriptors even if dmac
is busy. Prepare != start
> +	imxdmac->status = DMA_IN_PROGRESS;
> +
> +	ret = imx_dma_config_channel(imxdmac->imxdma_channel,
> +			       IMX_DMA_MEMSIZE_32 | IMX_DMA_TYPE_LINEAR,
> +			       IMX_DMA_MEMSIZE_32 | IMX_DMA_TYPE_LINEAR,
> +			       0, 0);
> +	if (ret)
> +		return NULL;
> +
> +	ret = imx_dma_setup_single(imxdmac->imxdma_channel, src, len,
> +				   dest, DMA_MODE_WRITE);
> +	if (ret)
> +		return NULL;
> +
> +	return &imxdmac->desc;
> +}
> +
>  static void imxdma_issue_pending(struct dma_chan *chan)
>  {
>  	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
> @@ -349,6 +380,7 @@ static int __init imxdma_probe(struct platform_device *pdev)
>  
>  	dma_cap_set(DMA_SLAVE, imxdma->dma_device.cap_mask);
>  	dma_cap_set(DMA_CYCLIC, imxdma->dma_device.cap_mask);
> +	dma_cap_set(DMA_MEMCPY, imxdma->dma_device.cap_mask);
>  
>  	/* Initialize channel parameters */
>  	for (i = 0; i < MAX_DMA_CHANNELS; i++) {
> @@ -382,11 +414,13 @@ static int __init imxdma_probe(struct platform_device *pdev)
>  	imxdma->dma_device.device_tx_status = imxdma_tx_status;
>  	imxdma->dma_device.device_prep_slave_sg = imxdma_prep_slave_sg;
>  	imxdma->dma_device.device_prep_dma_cyclic = imxdma_prep_dma_cyclic;
> +	imxdma->dma_device.device_prep_dma_memcpy = imxdma_prep_dma_memcpy;
>  	imxdma->dma_device.device_control = imxdma_control;
>  	imxdma->dma_device.device_issue_pending = imxdma_issue_pending;
>  
>  	platform_set_drvdata(pdev, imxdma);
>  
> +	imxdma->dma_device.copy_align = 2; /* 2^2 = 4 bytes alignment */
what is this magic number?
>  	imxdma->dma_device.dev->dma_parms = &imxdma->dma_parms;
>  	dma_set_max_seg_size(imxdma->dma_device.dev, 0xffffff);
>  


-- 
~Vinod

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