[PATCH] mtd: nand: pxa3xx: Incorrect bitflip return on page read

[Michael Nazzareno Trimarchi]

On Mon, Apr 29, 2024 at 6:22 PM Chris Packham <judge.packham at gmail.com> wrote:
>
> On Sun, Apr 28, 2024 at 4:15 AM Ravi Minnikanti <rminnikanti at marvell.com> wrote:
> >
> > Once a page is read with higher bitflips all subsequent reads
> > are returning the same bitflip value even though they have none.
> > max_bitflip variable is not being reset to 0 across page reads.
> >
> > This is causing problems like incorrectly
> > marking erase blocks bad by UBI and causing read failures.
> >
> > Verified the change with both MTD reads and UBI.
> > This change is inline with other NFC drivers.
> >
> > Sample error log where a block is marked bad incorrectly:
> >
> > ubi0: fixable bit-flip detected at PEB 125
> > ubi0: run torture test for PEB 125
> > ubi0: fixable bit-flip detected at PEB 125
> > ubi0 error: torture_peb: read problems on freshly erased PEB 125,
> > must be bad
> > ubi0 error: erase_worker: failed to erase PEB 125, error -5
> > ubi0: mark PEB 125 as bad
> >
> > Signed-off-by: rminnikanti <rminnikanti at marvell.com>
>
> Looks good to me
>
> Reviewed-by: Chris Packham <judge.packham at gmail.com>
>
> > ---
> >  drivers/mtd/nand/raw/pxa3xx_nand.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/mtd/nand/raw/pxa3xx_nand.c b/drivers/mtd/nand/raw/pxa3xx_nand.c
> > index 1d9a6d107b..d2a4faad56 100644
> > --- a/drivers/mtd/nand/raw/pxa3xx_nand.c
> > +++ b/drivers/mtd/nand/raw/pxa3xx_nand.c
> > @@ -800,6 +800,11 @@ static void prepare_start_command(struct pxa3xx_nand_info *info, int command)
> >         info->ecc_err_cnt       = 0;
> >         info->ndcb3             = 0;
> >         info->need_wait         = 0;
> > +       /*
> > +        * Reset max_bitflips to zero. Once command is complete,
> > +        * max_bitflips for this READ is returned in ecc.read_page()
> > +        */
> > +       info->max_bitflips      = 0;
> >

Why this should not be put to 0 in read_page instead on prepare_start_command?

Michael

> >         switch (command) {
> >         case NAND_CMD_READ0:
> > --
> > 2.17.1

-- 
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael at amarulasolutions.com
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