linux-kernel - Re: [PATCH] mtd: spi-nor: cadence-quadspi: Use proper enum for dma_unmap

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Date:   Tue, 25 Sep 2018 10:24:04 +0300
From:   Tudor Ambarus <tudor.ambarus@...rochip.com>
To:     Nathan Chancellor <natechancellor@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <boris.brezillon@...tlin.com>
CC:     Richard Weinberger <richard@....at>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mtd: spi-nor: cadence-quadspi: Use proper enum for
 dma_unmap_single

Hi, Nathan,

On 09/21/2018 01:29 PM, Nathan Chancellor wrote:
> Clang warns when one enumerated type is converted implicitly to another.
> 
> drivers/mtd/spi-nor/cadence-quadspi.c:962:47: warning: implicit
> conversion from enumeration type 'enum dma_transfer_direction' to
> different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
>         dma_dst = dma_map_single(nor->dev, buf, len, DMA_DEV_TO_MEM);
>                   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
> ./include/linux/dma-mapping.h:428:66: note: expanded from macro
> 'dma_map_single'
> #define dma_map_single(d, a, s, r) dma_map_single_attrs(d, a, s, r, 0)
>                                    ~~~~~~~~~~~~~~~~~~~~          ^
> drivers/mtd/spi-nor/cadence-quadspi.c:997:43: warning: implicit
> conversion from enumeration type 'enum dma_transfer_direction' to
> different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
>         dma_unmap_single(nor->dev, dma_dst, len, DMA_DEV_TO_MEM);
>         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
> ./include/linux/dma-mapping.h:429:70: note: expanded from macro
> 'dma_unmap_single'
> #define dma_unmap_single(d, a, s, r) dma_unmap_single_attrs(d, a, s, r, 0)
>                                      ~~~~~~~~~~~~~~~~~~~~~~          ^
> 2 warnings generated.
> 
> Use the proper enums from dma_data_direction to satisfy Clang.
> 
> DMA_TO_DEVICE = DMA_MEM_TO_DEV = 1
> DMA_FROM_DEVICE = DMA_DEV_TO_MEM = 2
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/108
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> ---
>  drivers/mtd/spi-nor/cadence-quadspi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
> index 8e714fbfa521..d0e57ac81098 100644
> --- a/drivers/mtd/spi-nor/cadence-quadspi.c
> +++ b/drivers/mtd/spi-nor/cadence-quadspi.c
> @@ -959,7 +959,7 @@ static int cqspi_direct_read_execute(struct spi_nor *nor, u_char *buf,
>  		return 0;
>  	}
>  
> -	dma_dst = dma_map_single(nor->dev, buf, len, DMA_DEV_TO_MEM);
> +	dma_dst = dma_map_single(nor->dev, buf, len, DMA_FROM_DEVICE);
>  	if (dma_mapping_error(nor->dev, dma_dst)) {
>  		dev_err(nor->dev, "dma mapping failed\n");
>  		return -ENOMEM;
> @@ -994,7 +994,7 @@ static int cqspi_direct_read_execute(struct spi_nor *nor, u_char *buf,
>  	}
>  
>  err_unmap:
> -	dma_unmap_single(nor->dev, dma_dst, len, DMA_DEV_TO_MEM);
> +	dma_unmap_single(nor->dev, dma_dst, len, DMA_TO_DEVICE);

Should have used DMA_FROM_DEVICE, as you did above. Otherwise looks good.

Cheers,
ta