Re: [PATCH 2/2] mtd: rawnand: brcmnand: Ecc error handling on EDU transfers

Miquel Raynal
2020-06-11T07:27:20Z

Hi Kamal,

Kamal Dasu <kdasu.kdev@gmail.com> wrote on Thu, 11 Jun 2020 01:44:54
-0400:

> Implemented ECC correctable and uncorrectable error handling for EDU

Implement?

> reads. If ECC correctable bitflips are encountered on EDU transfer,

extra space ^

> read page again using pio, This is needed due to a controller lmitation

s/pio/PIO/

> where read and corrected data is not transferred to the DMA buffer on ECC
> errors. This holds true for ECC correctable errors beyond set threshold.

error.

Not sure what the last sentence means?

>
> Fixes: a5d53ad26a8b ("mtd: rawnand: brcmnand: Add support for flash-edu for dma transfers")
> Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
> ---

Minor nits below :)

> drivers/mtd/nand/raw/brcmnand/brcmnand.c | 26 ++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> index 0c1d6e543586..d7daa83c8a58 100644
> --- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> @@ -1855,6 +1855,22 @@ static int brcmnand_edu_trans(struct brcmnand_host *host, u64 addr, u32 *buf,
> edu_writel(ctrl, EDU_STOP, 0); /* force stop */
> edu_readl(ctrl, EDU_STOP);
>
> + if (ret == 0 && edu_cmd == EDU_CMD_READ) {

!ret

> + u64 err_addr = 0;
> +
> + /*
> + * check for ecc errors here, subpage ecc erros are
> + * retained in ecc error addr register

s/ecc/ECC/
s/erros/errors/
s/addr/address/

> + */
> + err_addr = brcmnand_get_uncorrecc_addr(ctrl);
> + if (!err_addr) {
> + err_addr = brcmnand_get_correcc_addr(ctrl);
> + if (err_addr)
> + ret = -EUCLEAN;
> + } else
> + ret = -EBADMSG;

I don't like very much to see these values being used within NAND
controller drivers but I see it's already the cause, so I guess I can
live with that.

> + }
> +
> return ret;
> }
>
> @@ -2058,6 +2074,7 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,
> u64 err_addr = 0;
> int err;
> bool retry = true;
> + bool edu_read = false;
>
> dev_dbg(ctrl->dev, "read %llx -> %p\n", (unsigned long long)addr, buf);
>
> @@ -2075,6 +2092,10 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,
> else
> return -EIO;
> }
> +
> + if (has_edu(ctrl))
> + edu_read = true;

You don't need this extra value, you already have the cmd parameter
which tells you if it is a read or a write. You might even want to
create a if block so set dir and edu_cmd and eventually a local
edu_read if you think it still makes sense.

> +
> } else {
> if (oob)
> memset(oob, 0x99, mtd->oobsize);
> @@ -2122,6 +2143,11 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,
> if (mtd_is_bitflip(err)) {
> unsigned int corrected = brcmnand_count_corrected(ctrl);
>
> + /* in case of edu correctable error we read again using pio */

s/edu/EDU/ ?
s/pio/PIO/

> + if (edu_read)
> + err = brcmnand_read_by_pio(mtd, chip, addr, trans, buf,
> + oob, &err_addr);
> +
> dev_dbg(ctrl->dev, "corrected error at 0x%llx\n",
> (unsigned long long)err_addr);
> mtd->ecc_stats.corrected += corrected;

Thanks,
Miquèl