linux-kernel - Re: [PATCH 5/5] dmaengine: sprd: Add 'device_config' and 'device_prep_slave

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Date:   Wed, 11 Apr 2018 15:10:01 +0530
From:   Vinod Koul <vinod.koul@...el.com>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     dan.j.williams@...el.com, eric.long@...eadtrum.com,
        broonie@...nel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] dmaengine: sprd: Add 'device_config' and
 'device_prep_slave_sg' interfaces

On Tue, Apr 10, 2018 at 03:46:07PM +0800, Baolin Wang wrote:
> This patch adds the 'device_config' and 'device_prep_slave_sg' interfaces
> for users to configure DMA.
> 
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> ---
>  drivers/dma/sprd-dma.c |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 48 insertions(+)
> 
> diff --git a/drivers/dma/sprd-dma.c b/drivers/dma/sprd-dma.c
> index f8038de..c923fb0 100644
> --- a/drivers/dma/sprd-dma.c
> +++ b/drivers/dma/sprd-dma.c
> @@ -869,6 +869,52 @@ static int sprd_dma_config(struct dma_chan *chan, struct sprd_dma_desc *sdesc,
>  	return vchan_tx_prep(&schan->vc, &sdesc->vd, flags);
>  }
>  
> +static struct dma_async_tx_descriptor *
> +sprd_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
> +		       unsigned int sglen, enum dma_transfer_direction dir,
> +		       unsigned long flags, void *context)
> +{
> +	struct sprd_dma_chn *schan = to_sprd_dma_chan(chan);
> +	struct sprd_dma_config *slave_cfg = &schan->slave_cfg;
> +	struct sprd_dma_desc *sdesc;
> +	struct scatterlist *sg;
> +	int ret, i;
> +
> +	/* TODO: now we only support one sg for each DMA configuration. */
> +	if (!is_slave_direction(slave_cfg->config.direction) || sglen > 1)

the slave direction check seems wrong to me. .device_config shall give you
dma_slave_config. You should check here if dir passed is slave or not. If
you want to check parameters in slave_config then please use .device_config

> +		return NULL;
> +
> +	sdesc = kzalloc(sizeof(*sdesc), GFP_NOWAIT);
> +	if (!sdesc)
> +		return NULL;
> +
> +	for_each_sg(sgl, sg, sglen, i) {
> +		if (slave_cfg->config.direction == DMA_MEM_TO_DEV)
> +			slave_cfg->config.src_addr = sg_dma_address(sg);

Nope slave_config specifies peripheral address and not memory one passed here

-- 
~Vinod