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Date:   Wed, 10 Apr 2019 16:29:27 +0200
From:   Boris Brezillon <boris.brezillon@collabora.com>
To:     YueHaibing <yuehaibing@huawei.com>
Cc:     <miquel.raynal@bootlin.com>, <richard@nod.at>,
        <computersforpeace@gmail.com>, <marek.vasut@gmail.com>,
        <paul.burton@mips.com>, <bbrezillon@kernel.org>,
        <linux-kernel@vger.kernel.org>, <linux-mtd@lists.infradead.org>
Subject: Re: [PATCH] mtd: nand: Fix build error while
 CONFIG_MTD_NAND_ECC_SW_BCH is set to module
Message-ID: <20190410162927.17ea678b@collabora.com>
In-Reply-To: <8b020124-4008-6081-c04c-eaefb7875878@huawei.com>
References: <20190410130747.35692-1-yuehaibing@huawei.com>
        <20190410153920.68267a1a@collabora.com>
        <20190410155856.655122c8@collabora.com>
        <8b020124-4008-6081-c04c-eaefb7875878@huawei.com>
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On Wed, 10 Apr 2019 22:22:16 +0800
YueHaibing <yuehaibing@huawei.com> wrote:

> On 2019/4/10 21:58, Boris Brezillon wrote:
> > On Wed, 10 Apr 2019 15:39:28 +0200
> > Boris Brezillon <boris.brezillon@collabora.com> wrote:
> >   
> >> On Wed, 10 Apr 2019 21:07:47 +0800
> >> Yue Haibing <yuehaibing@huawei.com> wrote:
> >>  
> >>> From: YueHaibing <yuehaibing@huawei.com>
> >>>
> >>> Fix gcc build error while CONFIG_MTD_NAND_ECC_SW_BCH
> >>> is set to module:
> >>>
> >>> drivers/mtd/nand/raw/nand_base.o: In function `nand_cleanup':
> >>> (.text+0xef6): undefined reference to `nand_bch_free'
> >>> drivers/mtd/nand/raw/nand_base.o: In function `nand_scan_tail':
> >>> nand_base.c:(.text+0xa101): undefined reference to `nand_bch_calculate_ecc'
> >>> nand_base.c:(.text+0xa120): undefined reference to `nand_bch_correct_data'
> >>> nand_base.c:(.text+0xa269): undefined reference to `nand_bch_init'
> >>>
> >>> CONFIG_MTD_NAND_ECC_SW_BCH should not be set to M,
> >>> because MTD_RAW_NAND need it while linked.
> >>>
> >>> Reported-by: Hulk Robot <hulkci@huawei.com>
> >>> Fixes: 193bd4002644 ("mtd: nand: add software BCH ECC support"    
> >>
> >> Nope, it's not this one that introduced the regression.
> >>
> >>
> >>  
> >>> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> >>> ---
> >>>  drivers/mtd/nand/raw/Kconfig | 2 +-
> >>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
> >>> index 615d738..0500c42 100644
> >>> --- a/drivers/mtd/nand/raw/Kconfig
> >>> +++ b/drivers/mtd/nand/raw/Kconfig
> >>> @@ -22,7 +22,7 @@ menuconfig MTD_RAW_NAND
> >>>  if MTD_RAW_NAND
> >>>  
> >>>  config MTD_NAND_ECC_SW_BCH
> >>> -	tristate "Support software BCH ECC"
> >>> +	bool "Support software BCH ECC"
> >>>  	select BCH
> >>>  	default n
> >>>  	help    
> >>
> >> Should be fixed with the following diff squashed into:
> >>
> >> 51ef1d0b2095 ("mtd: nand: Clarify Kconfig entry for software BCH ECC algorithm")
> >>  
> >> --->8---    
> >> diff --git a/include/linux/mtd/nand_bch.h b/include/linux/mtd/nand_bch.h
> >> index b8106651f807..06ce2b655c13 100644
> >> --- a/include/linux/mtd/nand_bch.h
> >> +++ b/include/linux/mtd/nand_bch.h
> >> @@ -15,7 +15,7 @@ struct mtd_info;
> >>  struct nand_chip;
> >>  struct nand_bch_control;
> >>  
> >> -#if defined(CONFIG_MTD_NAND_ECC_BCH)
> >> +#if defined(CONFIG_MTD_NAND_ECC_SW_BCH)
> >>  
> >>  static inline int mtd_nand_has_bch(void) { return 1; }
> >>  
> >> @@ -39,7 +39,7 @@ struct nand_bch_control *nand_bch_init(struct mtd_info *mtd);
> >>   */
> >>  void nand_bch_free(struct nand_bch_control *nbc);
> >>  
> >> -#else /* !CONFIG_MTD_NAND_ECC_BCH */
> >> +#else /* !CONFIG_MTD_NAND_ECC_SW_BCH */
> >>  
> >>  static inline int mtd_nand_has_bch(void) { return 0; }
> >>  
> >> @@ -64,6 +64,6 @@ static inline struct nand_bch_control *nand_bch_init(struct mtd_info *mtd)
> >>  
> >>  static inline void nand_bch_free(struct nand_bch_control *nbc) {}
> >>  
> >> -#endif /* CONFIG_MTD_NAND_ECC_BCH */
> >> +#endif /* CONFIG_MTD_NAND_ECC_SW_BCH */
> >>  
> >>  #endif /* __MTD_NAND_BCH_H__ */  
> > 
> > Sorry, I didn't look at the right branch, this part of the code was
> > correct, but we still have a problem to express the RAW_NAND(y) ->
> > SW_BCH(y) dependency.  
> 
> It seems this dependency is not always need,
> 
> case MTD_RAW_NAND set to y works well while CONFIG_MTD_NAND_ECC_SW_BCH is not set.

Yes, I know, but forcing nand_bch to a be a boolean is not the right
solution either, hence my suggestion to use 'imply'.