linux-kernel - Re: [PATCH] mtd: spinand: fix error read return value

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Date:   Wed, 19 Jun 2019 18:18:32 +0200
From:   Boris Brezillon <boris.brezillon@...labora.com>
To:     Schrempf Frieder <frieder.schrempf@...tron.de>
Cc:     liaoweixiong <liaoweixiong@...winnertech.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Richard Weinberger <richard@....at>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Chuanhong Guo <gch981213@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Frieder Schrempf <frieder.schrempf@...eet.de>,
        Clément Péron <peron.clem@...il.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        "Peter Pan" <peterpandong@...ron.com>
Subject: Re: [PATCH] mtd: spinand: fix error read return value

On Wed, 19 Jun 2019 14:02:14 +0000
Schrempf Frieder <frieder.schrempf@...tron.de> wrote:

> On 19.06.19 15:46, Boris Brezillon wrote:
> > Hi liaoweixiong,
> > 
> > On Wed, 19 Jun 2019 21:13:24 +0800
> > liaoweixiong <liaoweixiong@...winnertech.com> wrote:
> >   
> >> In function spinand_mtd_read, if the last page to read occurs bitflip,
> >> this function will return error value because veriable ret not equal to 0.  
> > 
> > Actually, that's exactly what the MTD core expects (see [1]), so you're
> > the one introducing a regression here.  
> 
> To me it looks like the patch description is somewhat incorrect, but the 
> fix itself looks okay, unless I'm getting it wrong.
> 
> In case of the last page containing bitflips (ret > 0), 
> spinand_mtd_read() will return that number of bitflips for the last 
> page. But to me it looks like it should instead return max_bitflips like 
> it does when the last page read returns with 0.

Oh, you're right. liaoweixiong, can you adjust the commit message
accordingly?

> 
> >>
> >> Signed-off-by: liaoweixiong <liaoweixiong@...winnertech.com>
> >> ---
> >>   drivers/mtd/nand/spi/core.c | 2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> >> index 556bfdb..6b9388d 100644
> >> --- a/drivers/mtd/nand/spi/core.c
> >> +++ b/drivers/mtd/nand/spi/core.c
> >> @@ -511,12 +511,12 @@ static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,
> >>   		if (ret == -EBADMSG) {
> >>   			ecc_failed = true;
> >>   			mtd->ecc_stats.failed++;
> >> -			ret = 0;
> >>   		} else {
> >>   			mtd->ecc_stats.corrected += ret;
> >>   			max_bitflips = max_t(unsigned int, max_bitflips, ret);
> >>   		}
> >>   
> >> +		ret = 0;
> >>   		ops->retlen += iter.req.datalen;
> >>   		ops->oobretlen += iter.req.ooblen;
> >>   	}  
> > 
> > [1]https://elixir.bootlin.com/linux/latest/source/drivers/mtd/mtdcore.c#L1209
> > 
> > ______________________________________________________
> > Linux MTD discussion mailing list
> > http://lists.infradead.org/mailman/listinfo/linux-mtd/
> >  

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