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Date:   Wed, 10 Apr 2019 19:03:28 +0200
From:   Boris Brezillon <boris.brezillon@collabora.com>
To:     Miquel Raynal <miquel.raynal@bootlin.com>
Cc:     YueHaibing <yuehaibing@huawei.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: <20190410190328.433a954f@collabora.com>
In-Reply-To: <20190410181843.489a4e33@xps13>
References: <20190410130747.35692-1-yuehaibing@huawei.com>
        <20190410153920.68267a1a@collabora.com>
        <20190410155856.655122c8@collabora.com>
        <8b020124-4008-6081-c04c-eaefb7875878@huawei.com>
        <20190410162927.17ea678b@collabora.com>
        <41165c39-da0c-0f15-87f9-4fb588b77dcc@huawei.com>
        <20190410181843.489a4e33@xps13>
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On Wed, 10 Apr 2019 18:18:43 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> Hi YueHaibing,
> 
> YueHaibing <yuehaibing@huawei.com> wrote on Wed, 10 Apr 2019 23:03:24
> +0800:
> 
> > On 2019/4/10 22:29, Boris Brezillon wrote:  
> > > 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'.    
> 
> Why exactly? SW BCH is going to be converted to the generic ECC engine
> abstraction and IIRC you told me that it would not be problematic to
> turn it into a boolean?

Yes, I told you we should turn it into a boolean and embed the code in
the nandcore.o object which can itself be linked as a module or embedded
in the kernel image (see above for a version adapted for nand.o). That's
not exactly what Yue proposed.

--->8---
diff --git a/drivers/mtd/devices/Kconfig b/drivers/mtd/devices/Kconfig
index 7fcdaf6c279d..f9258d666846 100644
--- a/drivers/mtd/devices/Kconfig
+++ b/drivers/mtd/devices/Kconfig
@@ -207,7 +207,7 @@ comment "Disk-On-Chip Device Drivers"
 config MTD_DOCG3
        tristate "M-Systems Disk-On-Chip G3"
        select BCH
-       select BCH_CONST_PARAMS if !CONFIG_MTD_NAND_ECC_SW_BCH
+       select BCH_CONST_PARAMS if !MTD_NAND_ECC_SW_BCH
        select BITREVERSE
        help
          This provides an MTD device driver for the M-Systems DiskOnChip
diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
index 615d738be411..0500c42f31cb 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
diff --git a/drivers/mtd/nand/raw/Makefile b/drivers/mtd/nand/raw/Makefile
index 8bc6faaa3bc7..d644185fa18d 100644
--- a/drivers/mtd/nand/raw/Makefile
+++ b/drivers/mtd/nand/raw/Makefile
@@ -2,7 +2,6 @@
 
 obj-$(CONFIG_MTD_RAW_NAND)             += nand.o
 obj-$(CONFIG_MTD_NAND_ECC_SW_HAMMING)  += nand_ecc.o
-obj-$(CONFIG_MTD_NAND_ECC_SW_BCH)      += nand_bch.o
 obj-$(CONFIG_MTD_SM_COMMON)            += sm_common.o
 
 obj-$(CONFIG_MTD_NAND_CAFE)            += cafe_nand.o
@@ -68,3 +67,5 @@ nand-objs += nand_macronix.o
 nand-objs += nand_micron.o
 nand-objs += nand_samsung.o
 nand-objs += nand_toshiba.o
+nand-objs-$(CONFIG_MTD_NAND_ECC_SW_BCH)        += nand_bch.o
+nand-objs += $(nand-objs-y)