Re: [PATCH v4 5/7] mtd: rawnand: Support bad block markers in first, second or last page

[Schrempf Frieder <frieder.schrempf@kontron.de>]

On 04.03.19 12:21, Miquel Raynal wrote:
> Hi Schrempf,
> 
> Schrempf Frieder <frieder.schrempf@kontron.de> wrote on Mon, 18 Feb
> 2019 10:42:45 +0000:
> 
>> From: Frieder Schrempf <frieder.schrempf@kontron.de>
>>
>> Currently supported bad block marker positions within the block are:
>> * in first page only
>> * in last page only
>> * in first or second page
>>
>> Some ESMT NANDs are known to have been shipped by the manufacturer
>> with bad block markers in the first or last page, instead of the
>> first or second page.
>>
>> Also the datasheets for Cypress/Spansion/AMD NANDs claim that the
>> first, second *and* last page needs to be checked.
>>
>> Therefore we make it possible to set NAND_BBM_FIRSTPAGE,
>> NAND_BBM_SECONDPAGE and NAND_BBM_LASTPAGE independently in any
>> combination.
>>
>> To simplify the code, the logic to evaluate the flags is moved to a
>> a new function nand_bbm_get_next_page().
>>
>> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
>> Reviewed-by: Boris Brezillon <bbrezillon@kernel.org>
>> ---
>>   drivers/mtd/nand/raw/internals.h |  1 +
>>   drivers/mtd/nand/raw/nand_base.c | 62 ++++++++++++++++++++++++-----------
>>   drivers/mtd/nand/raw/nand_bbt.c  | 29 +++++++---------
>>   3 files changed, 55 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/raw/internals.h b/drivers/mtd/nand/raw/internals.h
>> index fbf6ca015cd7..97ae67e009d5 100644
>> --- a/drivers/mtd/nand/raw/internals.h
>> +++ b/drivers/mtd/nand/raw/internals.h
>> @@ -76,6 +76,7 @@ extern const struct nand_manufacturer_ops toshiba_nand_manuf_ops;
>>   
>>   /* Core functions */
>>   const struct nand_manufacturer *nand_get_manufacturer(u8 id);
>> +int nand_bbm_get_next_page(struct nand_chip *chip, int page);
>>   int nand_markbad_bbm(struct nand_chip *chip, loff_t ofs);
>>   int nand_erase_nand(struct nand_chip *chip, struct erase_info *instr,
>>   		    int allowbbt);
>> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
>> index 9ef7b86cdc42..7bc20c1fe23c 100644
>> --- a/drivers/mtd/nand/raw/nand_base.c
>> +++ b/drivers/mtd/nand/raw/nand_base.c
>> @@ -285,6 +285,31 @@ static void nand_release_device(struct nand_chip *chip)
>>   	spin_unlock(&chip->controller->lock);
>>   }
>>   
>> +/**
>> + * nand_bbm_get_next_page - Get the next page for bad block markers
>> + * @chip: NAND chip object
>> + * @index: Current page, only pages beyond this will be considered
> 
> Why pages *beyond*? Can't you change the logic to use the page from
> where to start searching? I am not sure such a change would be
> clearer in the rest of the code but I don't like the tests against
> "-1". Maybe you could just check negative values instead.

I guess I can change to use the page from where to start searching as a 
parameter. If that's what you mean (inclusive instead of exclusive)? 
Then the initial call would look like "nand_bbm_get_next_page(chip, 0)" 
instead of "nand_bbm_get_next_page(chip, -1)" which seems a bit clearer.

>> + *
>> + * Returns an integer that corresponds to the page offset within a block, for
>> + * a page that is used to store bad block markers. If no more pages are
>> + * available, -1 is returned.
>> + */
>> +int nand_bbm_get_next_page(struct nand_chip *chip, int page)
>> +{
>> +	struct mtd_info *mtd = nand_to_mtd(chip);
>> +	int last_page = ((mtd->erasesize - mtd->writesize) >>
>> +			 chip->page_shift) & chip->pagemask;
>> +
>> +	if (page < 0 && chip->options & NAND_BBM_FIRSTPAGE)
>> +		return 0;
>> +	else if (page < 1 && chip->options & NAND_BBM_SECONDPAGE)
>> +		return 1;
>> +	else if (page < last_page && chip->options & NAND_BBM_LASTPAGE)
>> +		return last_page;
>> +
>> +	return -1;
> 
> I would prefer a named value (like -EINVAL) and checks against a
> negative value (not -1).

Right, makes sense.

>> +}
>> +
>>   /**
>>    * nand_block_bad - [DEFAULT] Read bad block marker from the chip
>>    * @chip: NAND chip object
>> @@ -294,19 +319,14 @@ static void nand_release_device(struct nand_chip *chip)
>>    */
>>   static int nand_block_bad(struct nand_chip *chip, loff_t ofs)
>>   {
>> -	struct mtd_info *mtd = nand_to_mtd(chip);
>> -	int page, page_end, res;
>> +	int page_offset;
>> +	int res, first_page = (int)(ofs >> chip->page_shift) & chip->pagemask;
> 
> Maybe:
> 
>          int first_page, page_offset;
>          int res;
>          u8 bad;
> 
>          first_page = (int)(ofs >> chip->page_shift) & chip->pagemask;
>          page_offset = nand_bbm_get_next_page(chip, -1);

Looks better.

>>   	u8 bad;
>>   
>> -	if (chip->options & NAND_BBM_LASTPAGE)
>> -		ofs += mtd->erasesize - mtd->writesize;
>> +	page_offset = nand_bbm_get_next_page(chip, -1);
>>   
>> -	page = (int)(ofs >> chip->page_shift) & chip->pagemask;
>> -	page_end = page + (((chip->options & NAND_BBM_FIRSTPAGE) &&
>> -			    (chip->options & NAND_BBM_SECONDPAGE)) ? 2 : 1);
>> -
>> -	for (; page < page_end; page++) {
>> -		res = chip->ecc.read_oob(chip, page);
>> +	while (page_offset != -1) {
>> +		res = chip->ecc.read_oob(chip, first_page + page_offset);
>>   		if (res < 0)
>>   			return res;
>>   
>> @@ -318,6 +338,8 @@ static int nand_block_bad(struct nand_chip *chip, loff_t ofs)
>>   			res = hweight8(bad) < chip->badblockbits;
>>   		if (res)
>>   			return res;
>> +
>> +		page_offset = nand_bbm_get_next_page(chip, page_offset);
>>   	}
>>   
>>   	return 0;
>> @@ -528,7 +550,7 @@ static int nand_default_block_markbad(struct nand_chip *chip, loff_t ofs)
>>   	struct mtd_info *mtd = nand_to_mtd(chip);
>>   	struct mtd_oob_ops ops;
>>   	uint8_t buf[2] = { 0, 0 };
>> -	int ret = 0, res, i = 0;
>> +	int ret = 0, res, page_offset;
>>   
>>   	memset(&ops, 0, sizeof(ops));
>>   	ops.oobbuf = buf;
>> @@ -541,18 +563,18 @@ static int nand_default_block_markbad(struct nand_chip *chip, loff_t ofs)
>>   	}
>>   	ops.mode = MTD_OPS_PLACE_OOB;
>>   
>> -	/* Write to first/last page(s) if necessary */
>> -	if (chip->options & NAND_BBM_LASTPAGE)
>> -		ofs += mtd->erasesize - mtd->writesize;
>> -	do {
>> -		res = nand_do_write_oob(chip, ofs, &ops);
>> +	page_offset = nand_bbm_get_next_page(chip, -1);
>> +
>> +	while (page_offset != -1) {
>> +		res = nand_do_write_oob(chip,
>> +					ofs + page_offset * mtd->writesize,
>> +					&ops);
>> +
>>   		if (!ret)
>>   			ret = res;
>>   
>> -		i++;
>> -		ofs += mtd->writesize;
>> -	} while ((chip->options & NAND_BBM_FIRSTPAGE) &&
>> -		 (chip->options & NAND_BBM_SECONDPAGE) && i < 2);
>> +		page_offset = nand_bbm_get_next_page(chip, page_offset);
>> +	}
>>   
>>   	return ret;
>>   }
>> diff --git a/drivers/mtd/nand/raw/nand_bbt.c b/drivers/mtd/nand/raw/nand_bbt.c
>> index 7463afddc7ac..09603c502931 100644
>> --- a/drivers/mtd/nand/raw/nand_bbt.c
>> +++ b/drivers/mtd/nand/raw/nand_bbt.c
>> @@ -415,11 +415,12 @@ static void read_abs_bbts(struct nand_chip *this, uint8_t *buf,
>>   
>>   /* Scan a given block partially */
>>   static int scan_block_fast(struct nand_chip *this, struct nand_bbt_descr *bd,
>> -			   loff_t offs, uint8_t *buf, int numpages)
>> +			   loff_t offs, uint8_t *buf)
>>   {
>>   	struct mtd_info *mtd = nand_to_mtd(this);
>> +
>>   	struct mtd_oob_ops ops;
>> -	int j, ret;
>> +	int ret, page_offset;
>>   
>>   	ops.ooblen = mtd->oobsize;
>>   	ops.oobbuf = buf;
>> @@ -427,12 +428,15 @@ static int scan_block_fast(struct nand_chip *this, struct nand_bbt_descr *bd,
>>   	ops.datbuf = NULL;
>>   	ops.mode = MTD_OPS_PLACE_OOB;
>>   
>> -	for (j = 0; j < numpages; j++) {
>> +	page_offset = nand_bbm_get_next_page(this, -1);
>> +
>> +	while (page_offset != -1) {
>>   		/*
>>   		 * Read the full oob until read_oob is fixed to handle single
>>   		 * byte reads for 16 bit buswidth.
>>   		 */
>> -		ret = mtd_read_oob(mtd, offs, &ops);
>> +		ret = mtd_read_oob(mtd, offs + page_offset * mtd->writesize,
> 
> Can you add '(' & ')' please?

Sure

>> +				   &ops);
>>   		/* Ignore ECC errors when checking for BBM */
>>   		if (ret && !mtd_is_bitflip_or_eccerr(ret))
>>   			return ret;
>> @@ -440,8 +444,9 @@ static int scan_block_fast(struct nand_chip *this, struct nand_bbt_descr *bd,
>>   		if (check_short_pattern(buf, bd))
>>   			return 1;
>>   
>> -		offs += mtd->writesize;
>> +		page_offset = nand_bbm_get_next_page(this, page_offset);
>>   	}
>> +
>>   	return 0;
>>   }
>>   
>> @@ -460,18 +465,11 @@ static int create_bbt(struct nand_chip *this, uint8_t *buf,
>>   		      struct nand_bbt_descr *bd, int chip)
>>   {
>>   	struct mtd_info *mtd = nand_to_mtd(this);
>> -	int i, numblocks, numpages;
>> -	int startblock;
>> +	int i, numblocks, startblock;
>>   	loff_t from;
>>   
>>   	pr_info("Scanning device for bad blocks\n");
>>   
>> -	if ((this->options & NAND_BBM_FIRSTPAGE) &&
>> -	    (this->options & NAND_BBM_SECONDPAGE))
>> -		numpages = 2;
>> -	else
>> -		numpages = 1;
>> -
>>   	if (chip == -1) {
>>   		numblocks = mtd->size >> this->bbt_erase_shift;
>>   		startblock = 0;
>> @@ -488,15 +486,12 @@ static int create_bbt(struct nand_chip *this, uint8_t *buf,
>>   		from = (loff_t)startblock << this->bbt_erase_shift;
>>   	}
>>   
>> -	if (this->options & NAND_BBM_LASTPAGE)
>> -		from += mtd->erasesize - (mtd->writesize * numpages);
>> -
>>   	for (i = startblock; i < numblocks; i++) {
>>   		int ret;
>>   
>>   		BUG_ON(bd->options & NAND_BBT_NO_OOB);
>>   
>> -		ret = scan_block_fast(this, bd, from, buf, numpages);
>> +		ret = scan_block_fast(this, bd, from, buf);
>>   		if (ret < 0)
>>   			return ret;
>>   
> 
> 
> 
> 
> Thanks,
> Miquèl
>