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

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Date:   Tue, 25 Sep 2018 00:34:38 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Tudor Ambarus <tudor.ambarus@...rochip.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 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!

Nathan