Re: [PATCH] mtd: mtd_oobtest: Handle bitflips during reads

[Boris Brezillon <boris.brezillon@free-electrons.com>]

+David

On Thu, 11 Jan 2018 21:39:20 +0100
Miquel Raynal <miquel.raynal@free-electrons.com> wrote:

> Reads from NAND devices usually trigger bitflips, this is an expected
> behavior. While bitflips are under a given threshold, the MTD core
> returns 0. However, when the number of corrected bitflips is above this
> same threshold, -EUCLEAN is returned to inform the upper layer that this
> block is slightly dying and soon the ECC engine will be overtaken so
> actions should be taken to move the data out of it.
> 
> This particular condition should not be treated like an error and the
> test should continue.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>

Applied.

BTW, any volunteer to port this test in mtd-utils, or is there anything
in this test preventing us implementing it in userspace?

> ---
>  drivers/mtd/tests/oobtest.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/drivers/mtd/tests/oobtest.c b/drivers/mtd/tests/oobtest.c
> index 1cb3f7758fb6..766b2c385682 100644
> --- a/drivers/mtd/tests/oobtest.c
> +++ b/drivers/mtd/tests/oobtest.c
> @@ -193,6 +193,9 @@ static int verify_eraseblock(int ebnum)
>  		ops.datbuf    = NULL;
>  		ops.oobbuf    = readbuf;
>  		err = mtd_read_oob(mtd, addr, &ops);
> +		if (mtd_is_bitflip(err))
> +			err = 0;
> +
>  		if (err || ops.oobretlen != use_len) {
>  			pr_err("error: readoob failed at %#llx\n",
>  			       (long long)addr);
> @@ -227,6 +230,9 @@ static int verify_eraseblock(int ebnum)
>  			ops.datbuf    = NULL;
>  			ops.oobbuf    = readbuf;
>  			err = mtd_read_oob(mtd, addr, &ops);
> +			if (mtd_is_bitflip(err))
> +				err = 0;
> +
>  			if (err || ops.oobretlen != mtd->oobavail) {
>  				pr_err("error: readoob failed at %#llx\n",
>  						(long long)addr);
> @@ -286,6 +292,9 @@ static int verify_eraseblock_in_one_go(int ebnum)
>  
>  	/* read entire block's OOB at one go */
>  	err = mtd_read_oob(mtd, addr, &ops);
> +	if (mtd_is_bitflip(err))
> +		err = 0;
> +
>  	if (err || ops.oobretlen != len) {
>  		pr_err("error: readoob failed at %#llx\n",
>  		       (long long)addr);
> @@ -527,6 +536,9 @@ static int __init mtd_oobtest_init(void)
>  	pr_info("attempting to start read past end of OOB\n");
>  	pr_info("an error is expected...\n");
>  	err = mtd_read_oob(mtd, addr0, &ops);
> +	if (mtd_is_bitflip(err))
> +		err = 0;
> +
>  	if (err) {
>  		pr_info("error occurred as expected\n");
>  		err = 0;
> @@ -571,6 +583,9 @@ static int __init mtd_oobtest_init(void)
>  		pr_info("attempting to read past end of device\n");
>  		pr_info("an error is expected...\n");
>  		err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops);
> +		if (mtd_is_bitflip(err))
> +			err = 0;
> +
>  		if (err) {
>  			pr_info("error occurred as expected\n");
>  			err = 0;
> @@ -615,6 +630,9 @@ static int __init mtd_oobtest_init(void)
>  		pr_info("attempting to read past end of device\n");
>  		pr_info("an error is expected...\n");
>  		err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops);
> +		if (mtd_is_bitflip(err))
> +			err = 0;
> +
>  		if (err) {
>  			pr_info("error occurred as expected\n");
>  			err = 0;
> @@ -684,6 +702,9 @@ static int __init mtd_oobtest_init(void)
>  		ops.datbuf    = NULL;
>  		ops.oobbuf    = readbuf;
>  		err = mtd_read_oob(mtd, addr, &ops);
> +		if (mtd_is_bitflip(err))
> +			err = 0;
> +
>  		if (err)
>  			goto out;
>  		if (memcmpshow(addr, readbuf, writebuf,