Hi Zeng, On Fri, 8 Apr 2016 00:48:17 +0800 zengzhaoxiu@xxxxxxx wrote: > From: Zeng Zhaoxiu <zhaoxiu.zeng@xxxxxxxxx> > > If there is only one bit difference in the ECC, the function should return 1. > The result of "diff0 & ~(1<<fls(diff0))" is equal to diff0, so the function > actually returns -1. > > Here, we can use the simple expression "(diff0 & (diff0 - 1)) == 0" to determine > whether the diff0 has only one 1-bit. Missing Signed-off-by here. > --- > drivers/mtd/nand/s3c2410.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/mtd/nand/s3c2410.c b/drivers/mtd/nand/s3c2410.c > index 9c9397b..c9698cf 100644 > --- a/drivers/mtd/nand/s3c2410.c > +++ b/drivers/mtd/nand/s3c2410.c > @@ -542,7 +542,7 @@ static int s3c2410_nand_correct_data(struct mtd_info *mtd, u_char *dat, > diff0 |= (diff1 << 8); > diff0 |= (diff2 << 16); > > - if ((diff0 & ~(1<<fls(diff0))) == 0) > + if ((diff0 & (diff0 - 1)) == 0) Or just if (hweight_long((unsigned long)diff0) == 1) which is doing exactly what the comment says. BTW, I don't understand why the current code is wrong? To me, it seems it's correctly detecting the case where only a single bit is different. What are you trying to fix exactly? Best Regards, Boris -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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