Re: [PATCH v1] mtd: rawnand: Add Macronix NAND read retry support

[masonccyang@xxxxxxxxxxx]

Hi Miquel,
 
> > > > > > +
> > > > > > +      if (mxic->reliability_func & MACRONIX_READ_RETRY_BIT) {
> > > > > > +         chip->read_retries = MACRONIX_READ_RETRY_MODE + 1; 
> > > > > 
> > > > > Why +1 here, I am missing something? 
> > > > 
> > > > 
> > > > Without + 1, read retry mode is up to 4 rather than 5.
> > > > But this NAND device support read retry mode up to 5.
> > > > 
> > > 
> > > If there are 5 modes, you need to set 5 to chip->read_retries, not 
6.
> > > 
> > > If only 4 modes are used, there is probably a bug in the core that
> > > must be fixed, please do not workaround it in the driver! 
> > 
> > 
> > It seems some patches is needed in nand_base.c
> > 
-------------------------------------------------------------------------------------
> > diff --git a/drivers/mtd/nand/raw/nand_base.c 
> > b/drivers/mtd/nand/raw/nand_base.c
> > index ddd396e..56be3a9 100644
> > --- a/drivers/mtd/nand/raw/nand_base.c
> > +++ b/drivers/mtd/nand/raw/nand_base.c
> > @@ -3101,7 +3101,8 @@ static int nand_setup_read_retry(struct 
nand_chip 
> > *chip, int retry_mode)
> >  {
> >         pr_debug("setting READ RETRY mode %d\n", retry_mode);
> > 
> > -       if (retry_mode >= chip->read_retries)
> > +       if (retry_mode > chip->read_retries)
> 
> If I understand correctly, chip->read_retries is the total number of
> 'modes' so the last valid mode is indeed chip->read_retries -1.
> 
> I thought the problem would come from the core but I was wrong, you
> actually need a MACRONIX_NUM_READ_RETRY_MODES set to 6. Please have two
> defines if you need both (the first one being something like
> MACRONIX_MAXIMUM_READ_RETRY_MODE set to 5).

I have checked one of Micron's datasheet and it defined read-retry number 
= 8,
mode 0 ~ 7, 0 mean to disable read-retry.
Therefore, I will patch MACRONIX_NUM_READ_RETRY_MODES = 6.

thanks & best regards,
Mason
 



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