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

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Date:   Tue, 25 Sep 2018 11:18:16 +0300
From:   Tudor Ambarus <tudor.ambarus@...rochip.com>
To:     Nathan Chancellor <natechancellor@...il.com>
CC:     Marek Vasut <marek.vasut@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <boris.brezillon@...tlin.com>,
        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



On 09/25/2018 10:34 AM, Nathan Chancellor wrote:
> On Tue, Sep 25, 2018 at 10:24:04AM +0300, Tudor Ambarus wrote:
>> 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
> 
> Thank you very much for catching this, did several of these conversions
> back to back and didn't look closely at this. I just sent a v2, I
> appreciate the review!
I guess I have some problems with my email server. I receive just some of the
emails sent to linux-mtd@...ts.infradead.org. I haven't received your v2 and I
can't add my Reviewed-by tag there. But I checked v2 on
https://patchwork.ozlabs.org/patch/974269/, looks good, so:

Reviewed-by: Tudor Ambarus <tudor.ambarus@...rochip.com> for v2! :)

Best,
ta