[PATCH] mtd: nand: tango: Enforce DMA direction type

[Marc Gonzalez]

On 13/02/2017 10:45, Boris Brezillon wrote:

> do_dma() use an integer to pass the DMA data direction information and
> pass the same value to dmaengine_prep_slave_sg().
> 
> Currently, DMA_{FROM,TO}_DEVICE match DMA_{DEV_TO_MEM,MEM_TO_DEV}
> definitions so it works fine, but assuming this will always be the case
> is not safe.
> 
> Enforce enum dma_data_direction type in the function prototype and make
> the enum dma_data_direction -> enum dma_transfer_direction conversion
> explicit.
> 
> Reported-by: Richard Weinberger <richard at nod.at>
> Signed-off-by: Boris Brezillon <boris.brezillon at free-electrons.com>
> ---
>  drivers/mtd/nand/tango_nand.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/nand/tango_nand.c b/drivers/mtd/nand/tango_nand.c
> index 4a5e948c62df..9a0e2f85d865 100644
> --- a/drivers/mtd/nand/tango_nand.c
> +++ b/drivers/mtd/nand/tango_nand.c
> @@ -223,8 +223,8 @@ static void tango_dma_callback(void *arg)
>  	complete(arg);
>  }
>  
> -static int do_dma(struct tango_nfc *nfc, int dir, int cmd, const void *buf,
> -		  int len, int page)
> +static int do_dma(struct tango_nfc *nfc, enum dma_data_direction dir, int cmd,
> +		  const void *buf, int len, int page)
>  {
>  	void __iomem *addr = nfc->reg_base + NFC_STATUS;
>  	struct dma_chan *chan = nfc->chan;
> @@ -238,7 +238,10 @@ static int do_dma(struct tango_nfc *nfc, int dir, int cmd, const void *buf,
>  	if (dma_map_sg(chan->device->dev, &sg, 1, dir) != 1)
>  		return -EIO;
>  
> -	desc = dmaengine_prep_slave_sg(chan, &sg, 1, dir, DMA_PREP_INTERRUPT);
> +	desc = dmaengine_prep_slave_sg(chan, &sg, 1,
> +				       dir == DMA_FROM_DEVICE ?
> +				       DMA_DEV_TO_MEM : DMA_MEM_TO_DEV,
> +				       DMA_PREP_INTERRUPT);
>  	if (!desc)
>  		goto dma_unmap;
>  
> 

How about evaluating the ternary conditional into a temp var?

diff --git a/drivers/mtd/nand/tango_nand.c b/drivers/mtd/nand/tango_nand.c
index 4a5e948c62df..c3f145528f1d 100644
--- a/drivers/mtd/nand/tango_nand.c
+++ b/drivers/mtd/nand/tango_nand.c
@@ -231,6 +231,7 @@ static int do_dma(struct tango_nfc *nfc, int dir, int cmd, const void *buf,
        struct dma_async_tx_descriptor *desc;
        struct scatterlist sg;
        struct completion tx_done;
+       int xdir = dir == DMA_TO_DEVICE ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM;
        int err = -EIO;
        u32 res, val;
 
@@ -238,7 +239,7 @@ static int do_dma(struct tango_nfc *nfc, int dir, int cmd, const void *buf,
        if (dma_map_sg(chan->device->dev, &sg, 1, dir) != 1)
                return -EIO;
 
-       desc = dmaengine_prep_slave_sg(chan, &sg, 1, dir, DMA_PREP_INTERRUPT);
+       desc = dmaengine_prep_slave_sg(chan, &sg, 1, xdir, DMA_PREP_INTERRUPT);
        if (!desc)
                goto dma_unmap;