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Date:   Fri, 8 Feb 2019 11:11:59 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Kyungmin Park <kyungmin.park@...sung.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Wan ZongShun <mcuos.com@...il.com>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v2] mtd: rawnand: mark expected switch fall-throughs

Hey Miquel,

On 2/5/19 6:55 AM, Miquel Raynal wrote:
> Hi Gustavo,
> 
> "Gustavo A. R. Silva" <gustavo@...eddedor.com> wrote on Mon, 28 Jan
> 2019 12:15:20 -0600:
> 
>> In preparation to enabling -Wimplicit-fallthrough, mark switch
>> cases where we are expecting to fall through.
>>
>> This patch fixes the following warning:
>>
>> drivers/mtd/nand/onenand/onenand_base.c:3264:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/onenand/onenand_base.c:3288:17: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/raw/nand_base.c:5538:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/raw/nand_base.c:5557:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/raw/nand_base.c:5595:13: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/raw/nand_legacy.c:332:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/raw/nand_legacy.c:483:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/raw/nandsim.c:2254:22: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/raw/omap_elm.c:512:4: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/raw/omap_elm.c:517:4: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/raw/omap_elm.c:466:37: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/raw/omap_elm.c:471:37: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> drivers/mtd/nand/raw/nuc900_nand.c: In function ‘nuc900_nand_command_lp’:
>> ./arch/x86/include/asm/io.h:91:22: warning: this statement may fall through [-Wimplicit-fallthrough=]
>>  #define __raw_writel __writel
>> drivers/mtd/nand/raw/nuc900_nand.c:52:2: note: in expansion of macro ‘__raw_writel’
>>   __raw_writel((val), (dev)->reg + REG_SMCMD)
>>   ^~~~~~~~~~~~
>> drivers/mtd/nand/raw/nuc900_nand.c:196:3: note: in expansion of macro ‘write_cmd_reg’
>>    write_cmd_reg(nand, NAND_CMD_READSTART);
>>    ^~~~~~~~~~~~~
>> drivers/mtd/nand/raw/nuc900_nand.c:197:2: note: here
>>   default:
>>   ^~~~~~~
>>
>> Warning level 3 was used: -Wimplicit-fallthrough=3
>>
>> This patch is part of the ongoing efforts to enabling
>> -Wimplicit-fallthrough.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
>> ---
>> Changes in v2:
>>  - Add extra /* fall through */ comment in nandsim.c file.
>>
>>  drivers/mtd/nand/onenand/onenand_base.c | 2 ++
>>  drivers/mtd/nand/raw/diskonchip.c       | 1 +
>>  drivers/mtd/nand/raw/nand_base.c        | 3 +++
>>  drivers/mtd/nand/raw/nand_legacy.c      | 3 ++-
>>  drivers/mtd/nand/raw/nandsim.c          | 6 ++++--
>>  drivers/mtd/nand/raw/nuc900_nand.c      | 3 ++-
>>  drivers/mtd/nand/raw/omap_elm.c         | 4 ++++
>>  7 files changed, 18 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/onenand/onenand_base.c b/drivers/mtd/nand/onenand/onenand_base.c
>> index 4ca4b194e7d7..e9b71ad24f50 100644
>> --- a/drivers/mtd/nand/onenand/onenand_base.c
>> +++ b/drivers/mtd/nand/onenand/onenand_base.c
> 
> onenand changes should probably be in a separate patch prefixed
> 
>         mtd: onenand:
> 
> When you are unsure, please run
> 
>         git log --oneline --follow drivers/mtd/nand/onenand/
> 

OK. Got it.

>> @@ -3280,12 +3280,14 @@ static void onenand_check_features(struct mtd_info *mtd)
>>  			if ((this->version_id & 0xf) == 0xe)
>>  				this->options |= ONENAND_HAS_NOP_1;
>>  		}
>> +		/* fall through */
>>  
>>  	case ONENAND_DEVICE_DENSITY_2Gb:
>>  		/* 2Gb DDP does not have 2 plane */
>>  		if (!ONENAND_IS_DDP(this))
>>  			this->options |= ONENAND_HAS_2PLANE;
>>  		this->options |= ONENAND_HAS_UNLOCK_ALL;
>> +		/* fall through */
> 
> This looks strange.
> 
> In ONENAND_DEVICE_DENSITY_2Gb:
> ONENAND_HAS_UNLOCK_ALL is set unconditionally.
> 
> But then, under ONENAND_DEVICE_DENSITY_1Gb, the same option is set only
> if process is evaluated to true.
> 
> Same problem with ONENAND_HAS_2PLANE:
> - it is set in ONENAND_DEVICE_DENSITY_4Gb only if ONENAND_IS_DDP()
> - it is unset in ONENAND_DEVICE_DENSITY_2Gb only if !ONENAND_IS_DDP()
> 
> Maybe this portion should be reworked because I am unsure if this is a
> missing fall through or a bug.
> 

OK. Then, I should probably skip this file for now.

>>  
>>  	case ONENAND_DEVICE_DENSITY_1Gb:
>>  		/* A-Die has all block unlock */
>> diff --git a/drivers/mtd/nand/raw/diskonchip.c b/drivers/mtd/nand/raw/diskonchip.c
>> index 53f57e0f007e..ead54c90f2d1 100644
>> --- a/drivers/mtd/nand/raw/diskonchip.c
>> +++ b/drivers/mtd/nand/raw/diskonchip.c
>> @@ -1477,6 +1477,7 @@ static int __init doc_probe(unsigned long physadr)
>>  			break;
>>  		case DOC_ChipID_DocMilPlus32:
>>  			pr_err("DiskOnChip Millennium Plus 32MB is not supported, ignoring.\n");
>> +			/* fall through */
>>  		default:
>>  			ret = -ENODEV;
>>  			goto notfound;
> 
> This is fine.
> 
>> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
>> index 96cadead262e..e05ecf2e4269 100644
>> --- a/drivers/mtd/nand/raw/nand_base.c
>> +++ b/drivers/mtd/nand/raw/nand_base.c
>> @@ -5537,6 +5537,7 @@ static int nand_scan_tail(struct nand_chip *chip)
>>  		}
>>  		if (!ecc->read_page)
>>  			ecc->read_page = nand_read_page_hwecc_oob_first;
>> +		/* fall through */
>>  
>>  	case NAND_ECC_HW:
>>  		/* Use standard hwecc read page function? */
>> @@ -5556,6 +5557,7 @@ static int nand_scan_tail(struct nand_chip *chip)
>>  			ecc->read_subpage = nand_read_subpage;
>>  		if (!ecc->write_subpage && ecc->hwctl && ecc->calculate)
>>  			ecc->write_subpage = nand_write_subpage_hwecc;
>> +		/* fall through */
>>  
>>  	case NAND_ECC_HW_SYNDROME:
>>  		if ((!ecc->calculate || !ecc->correct || !ecc->hwctl) &&
>> @@ -5593,6 +5595,7 @@ static int nand_scan_tail(struct nand_chip *chip)
>>  			ecc->size, mtd->writesize);
>>  		ecc->mode = NAND_ECC_SOFT;
>>  		ecc->algo = NAND_ECC_HAMMING;
>> +		/* fall through */
>>  
>>  	case NAND_ECC_SOFT:
>>  		ret = nand_set_ecc_soft_ops(chip);
> 
> These three already are in nand/next.
> 

Great.

>> diff --git a/drivers/mtd/nand/raw/nand_legacy.c b/drivers/mtd/nand/raw/nand_legacy.c
>> index 43575943f13b..f2526ec616a6 100644
>> --- a/drivers/mtd/nand/raw/nand_legacy.c
>> +++ b/drivers/mtd/nand/raw/nand_legacy.c
>> @@ -331,6 +331,7 @@ static void nand_command(struct nand_chip *chip, unsigned int command,
>>  		 */
>>  		if (column == -1 && page_addr == -1)
>>  			return;
>> +		/* fall through */
>>  
>>  	default:
>>  		/*
>> @@ -483,7 +484,7 @@ static void nand_command_lp(struct nand_chip *chip, unsigned int command,
>>  		chip->legacy.cmd_ctrl(chip, NAND_CMD_NONE,
>>  				      NAND_NCE | NAND_CTRL_CHANGE);
>>  
>> -		/* This applies to read commands */
>> +		/* fall through - This applies to read commands */
>>  	default:
>>  		/*
>>  		 * If we don't have access to the busy pin, we apply the given
> 
> Already fixed in nand/next too.
> 

OK. Great.

>> diff --git a/drivers/mtd/nand/raw/nandsim.c b/drivers/mtd/nand/raw/nandsim.c
>> index 933d1a629c51..edf5fd3d5f07 100644
>> --- a/drivers/mtd/nand/raw/nandsim.c
>> +++ b/drivers/mtd/nand/raw/nandsim.c
>> @@ -2251,9 +2251,11 @@ static int __init ns_init_module(void)
>>  
>>  	switch (bbt) {
>>  	case 2:
>> -		 chip->bbt_options |= NAND_BBT_NO_OOB;
>> +		chip->bbt_options |= NAND_BBT_NO_OOB;
>> +		/* fall through */
>>  	case 1:
>> -		 chip->bbt_options |= NAND_BBT_USE_FLASH;
>> +		chip->bbt_options |= NAND_BBT_USE_FLASH;
>> +		/* fall through */
>>  	case 0:
>>  		break;
>>  	default:
> 
> This is fine.
> 
>> diff --git a/drivers/mtd/nand/raw/nuc900_nand.c b/drivers/mtd/nand/raw/nuc900_nand.c
>> index 38b1994e7ed3..56fa84029482 100644
>> --- a/drivers/mtd/nand/raw/nuc900_nand.c
>> +++ b/drivers/mtd/nand/raw/nuc900_nand.c
>> @@ -192,8 +192,9 @@ static void nuc900_nand_command_lp(struct nand_chip *chip,
>>  		return;
>>  
>>  	case NAND_CMD_READ0:
>> -
>>  		write_cmd_reg(nand, NAND_CMD_READSTART);
>> +		/* fall through */
>> +
>>  	default:
>>  
>>  		if (!chip->legacy.dev_ready) {
> 
> This is fine too.
> 
>> diff --git a/drivers/mtd/nand/raw/omap_elm.c b/drivers/mtd/nand/raw/omap_elm.c
>> index a3f32f939cc1..94c6401ef32f 100644
>> --- a/drivers/mtd/nand/raw/omap_elm.c
>> +++ b/drivers/mtd/nand/raw/omap_elm.c
>> @@ -465,11 +465,13 @@ static int elm_context_save(struct elm_info *info)
>>  					ELM_SYNDROME_FRAGMENT_5 + offset);
>>  			regs->elm_syndrome_fragment_4[i] = elm_read_reg(info,
>>  					ELM_SYNDROME_FRAGMENT_4 + offset);
>> +			/* fall through */
>>  		case BCH8_ECC:
>>  			regs->elm_syndrome_fragment_3[i] = elm_read_reg(info,
>>  					ELM_SYNDROME_FRAGMENT_3 + offset);
>>  			regs->elm_syndrome_fragment_2[i] = elm_read_reg(info,
>>  					ELM_SYNDROME_FRAGMENT_2 + offset);
>> +			/* fall through */
>>  		case BCH4_ECC:
>>  			regs->elm_syndrome_fragment_1[i] = elm_read_reg(info,
>>  					ELM_SYNDROME_FRAGMENT_1 + offset);
>> @@ -511,11 +513,13 @@ static int elm_context_restore(struct elm_info *info)
>>  					regs->elm_syndrome_fragment_5[i]);
>>  			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_4 + offset,
>>  					regs->elm_syndrome_fragment_4[i]);
>> +			/* fall through */
>>  		case BCH8_ECC:
>>  			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_3 + offset,
>>  					regs->elm_syndrome_fragment_3[i]);
>>  			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_2 + offset,
>>  					regs->elm_syndrome_fragment_2[i]);
>> +			/* fall through */
>>  		case BCH4_ECC:
>>  			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_1 + offset,
>>  					regs->elm_syndrome_fragment_1[i]);
> 
> And this is ok as well.
> 

I'll leave out the files that have already been addressed and send v3 shortly.

I appreciate your feedback.

Thanks
--
Gustavo

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