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Date: Tue, 21 Oct 2014 16:05:40 +0530
From: Vinod Koul <vinod.koul@intel.com>
To: Herve Codina <herve.codina@celad.com>
Subject: Re: [PATCH 1/2] mtd: atmel_nand: use __iowrite32_copy for 32 bitcopy
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On Tue, Oct 21, 2014 at 12:20:06PM +0200, Herve Codina wrote:
> Hi,
Please don't top post
> 
> I didn't go deeper in atmel_nand.c code to see other accesses but old
> copy use writel_relaxed which is a macro to __raw_writel((__force u32)
> cpu_to_le32(v),c)
> 
> __iowrite32_copy use directly __raw_writel(*src++, dst++)
> 
> So we skip cpu_to_le32. Is it ok for all system using atmel_nand ?
Also would be a good question if we need barriers as __iowrite32_copy()
doesn't guarantee any ordering.

-- 
~Vinod

> 
> Best regards,
> Herve Codina
> 
> 
> Le 21/10/2014 12:03, Josh Wu a écrit :
> > Hi, Vinod
> > 
> > On 10/21/2014 12:06 AM, Vinod Koul wrote:
> >> The driver was also using own method to do 32bit copy, turns out
> >> we have a kernel API so use that instead
> >>
> >> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
> > 
> > Thanks for the patch.
> > Acked-by: Josh Wu <josh.wu@atmel.com>
> > 
> > BTW, is there any similar kernel API that is for the read from io?
> > 
> > Best Regards,
> > Josh Wu
> > 
> >> ---
> >>   drivers/mtd/nand/atmel_nand.c |   10 +++-------
> >>   1 files changed, 3 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
> >> index e321c56..b03e80d 100644
> >> --- a/drivers/mtd/nand/atmel_nand.c
> >> +++ b/drivers/mtd/nand/atmel_nand.c
> >> @@ -265,14 +265,10 @@ static void memcpy32_fromio(void *trg, const void __iomem  *src, size_t size)
> >>   		*t++ = readl_relaxed(s++);
> >>   }
> >>   
> >> -static void memcpy32_toio(void __iomem *trg, const void *src, int size)
> >> +static inline void memcpy32_toio(void __iomem *trg, const void *src, int size)
> >>   {
> >> -	int i;
> >> -	u32 __iomem *t = trg;
> >> -	const u32 *s = src;
> >> -
> >> -	for (i = 0; i < (size >> 2); i++)
> >> -		writel_relaxed(*s++, t++);
> >> +	/* __iowrite32_copy use 32bit size values so divide by 4 */
> >> +	__iowrite32_copy(trg, src, size/4);
> >>   }
> >>   
> >>   /*
> > 

--