Message-ID: <20171219130353.4d0a3bee@bbrezillon>
Date:   Tue, 19 Dec 2017 13:03:53 +0100
From:   Boris Brezillon <boris.brezillon@...e-electrons.com>
To:     KOBAYASHI Yoshitake <yoshitake.kobayashi@...hiba.co.jp>
Cc:     richard@....at, dwmw2@...radead.org, computersforpeace@...il.com,
        marek.vasut@...il.com, cyrille.pitchen@...ev4u.fr,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next v3 2/2] mtd: nand: toshiba: Add support for
 Toshiba Memory BENAND (Built-in ECC NAND)

On Tue, 19 Dec 2017 21:01:47 +0900
KOBAYASHI Yoshitake <yoshitake.kobayashi@...hiba.co.jp> wrote:

> Thanks for reviewing the patches and taht is a good news for me about nand_exec_op().
> I'll change this patch as you suggested.
> I would like to make sure the following one.
> 
> >> @@ -70,6 +155,10 @@ static int toshiba_nand_init(struct nand_chip *chip)
> >>  	if (nand_is_slc(chip))
> >>  		chip->bbt_options |= NAND_BBT_SCAN2NDPAGE;
> >>  
> >> +	if (nand_is_slc(chip) && (chip->id.data[4] & 0x80) /* BENAND */ &&
> >> +	    (chip->ecc.mode == NAND_ECC_ON_DIE))
> >> +		toshiba_nand_benand_init(chip);
> >> +  
> > 
> > Please move this block to toshiba_nand_init().  
> 
> I think it's already in toshiba_nand_init().

My bad, I thought it was in the decode_id() function.

> 
> -- YOSHI
> 
> 
> On 2017/12/07 0:24, Boris Brezillon wrote:
> > On Wed,  6 Dec 2017 23:04:58 +0900
> > KOBAYASHI Yoshitake <yoshitake.kobayashi@...hiba.co.jp> wrote:
> >   
> >> This patch enables support for Toshiba Memory BENAND. This checks
> >> internal ECC status in read operation when using BENAND and selecting
> >> ECC mode as on-die.
> >>
> >> Signed-off-by: KOBAYASHI Yoshitake <yoshitake.kobayashi@...hiba.co.jp>
> >> ---
> >>  drivers/mtd/nand/nand_toshiba.c | 89 +++++++++++++++++++++++++++++++++++++++++
> >>  1 file changed, 89 insertions(+)
> >>
> >> diff --git a/drivers/mtd/nand/nand_toshiba.c b/drivers/mtd/nand/nand_toshiba.c
> >> index c2c141b..35c0ddf 100644
> >> --- a/drivers/mtd/nand/nand_toshiba.c
> >> +++ b/drivers/mtd/nand/nand_toshiba.c
> >> @@ -17,6 +17,91 @@
> >>  
> >>  #include <linux/mtd/rawnand.h>
> >>  
> >> +/* ECC Status Read Command for BENAND */
> >> +#define TOSHIBA_NAND_CMD_ECC_STATUS	0x7A
> >> +
> >> +/* Recommended to rewrite for BENAND */
> >> +#define TOSHIBA_NAND_STATUS_REWRITE_RECOMMENDED	BIT(3)
> >> +
> >> +static int toshiba_nand_benand_status_chk(struct mtd_info *mtd,
> >> +					  struct nand_chip *chip)
> >> +{
> >> +	unsigned int max_bitflips = 0;
> >> +	u8 status;
> >> +
> >> +	/* Check Read Status */
> >> +	chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1);
> >> +	status = chip->read_byte(mtd);  
> > 
> > Please use the recently introduced nand_status_op() helper.
> >   
> >> +
> >> +	/*
> >> +	 * TOSHIBA_NAND_CMD_ECC_STATUS is vendor specific command.
> >> +	 * Currently we have no way to send arbitrary sequences of
> >> +	 * CMD+ADDR+DATA cycles and thus cannot support this custom
> >> +	 * TOSHIBA_NAND_CMD_ECC_STATUS operation.  
> > 
> > That's about to change :-), if everything goes well, nand_exec_op()
> > should be available in 4.16.
> >   
> >> +	 * For now, we set max_bitflips mtd->bitflip_threshold.
> >> +	 */
> >> +	if (status & NAND_STATUS_FAIL) {
> >> +		/* uncorrectable */
> >> +		mtd->ecc_stats.failed++;
> >> +	} else if (status & TOSHIBA_NAND_STATUS_REWRITE_RECOMMENDED) {
> >> +		/* correctable */
> >> +		max_bitflips = mtd->bitflip_threshold;
> >> +		mtd->ecc_stats.corrected += max_bitflips;
> >> +	}
> >> +
> >> +	return max_bitflips;
> >> +}
> >> +
> >> +static int
> >> +toshiba_nand_read_page_benand(struct mtd_info *mtd,
> >> +			      struct nand_chip *chip, uint8_t *buf,
> >> +			      int oob_required, int page)
> >> +{
> >> +	nand_read_page_raw(mtd, chip, buf, oob_required, page);  
> > 
> > Please check the return code of nand_read_page_raw().
> >   
> >> +
> >> +	return toshiba_nand_benand_status_chk(mtd, chip);
> >> +}
> >> +
> >> +static int
> >> +toshiba_nand_read_subpage_benand(struct mtd_info *mtd,
> >> +				 struct nand_chip *chip, uint32_t data_offs,
> >> +				 uint32_t readlen, uint8_t *bufpoi, int page)
> >> +{
> >> +	uint8_t *p;
> >> +
> >> +	if (data_offs != 0)
> >> +		chip->cmdfunc(mtd, NAND_CMD_RNDOUT, data_offs, -1);
> >> +
> >> +	p = bufpoi + data_offs;
> >> +	chip->read_buf(mtd, p, readlen);  
> > 
> > The core is no longer sending the initial READ0 command, so this should
> > be turned into:
> > 
> > 	ret = nand_read_page_op(chip, data_offs, bufpoi + data_offs,
> > 				readlen);
> > 	if (ret)
> > 		return ret;
> > 		
> >   
> >> +
> >> +	return toshiba_nand_benand_status_chk(mtd, chip);
> >> +}
> >> +
> >> +static void toshiba_nand_benand_init(struct nand_chip *chip)
> >> +{
> >> +	struct mtd_info *mtd = nand_to_mtd(chip);
> >> +
> >> +	/*
> >> +	 * On BENAND, the entire OOB region can be used by the MTD user.
> >> +	 * The calculated ECC bytes are stored into other isolated
> >> +	 * area which is not accessible to users.
> >> +	 * This is why chip->ecc.bytes = 0.
> >> +	 */
> >> +	chip->ecc.bytes = 0;
> >> +	chip->ecc.size = 512;
> >> +	chip->ecc.strength = 8;
> >> +	chip->ecc.read_page = toshiba_nand_read_page_benand;
> >> +	chip->ecc.read_subpage = toshiba_nand_read_subpage_benand;
> >> +	chip->ecc.write_page = nand_write_page_raw;
> >> +	chip->ecc.read_page_raw = nand_read_page_raw;
> >> +	chip->ecc.write_page_raw = nand_write_page_raw;
> >> +
> >> +	chip->options |= NAND_SUBPAGE_READ;
> >> +
> >> +	mtd_set_ooblayout(mtd, &nand_ooblayout_lp_ops);
> >> +}
> >> +
> >>  static void toshiba_nand_decode_id(struct nand_chip *chip)
> >>  {
> >>  	struct mtd_info *mtd = nand_to_mtd(chip);
> >> @@ -70,6 +155,10 @@ static int toshiba_nand_init(struct nand_chip *chip)
> >>  	if (nand_is_slc(chip))
> >>  		chip->bbt_options |= NAND_BBT_SCAN2NDPAGE;
> >>  
> >> +	if (nand_is_slc(chip) && (chip->id.data[4] & 0x80) /* BENAND */ &&
> >> +	    (chip->ecc.mode == NAND_ECC_ON_DIE))
> >> +		toshiba_nand_benand_init(chip);
> >> +  
> > 
> > Please move this block to toshiba_nand_init().
> >   
> >>  	return 0;
> >>  }
> >>    
> > 
> > 
> >   
> 

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