linux-kernel - Re: [PATCH 2/2] mtd: nand: raw: brcmnand: fallback to detected ecc-strength, ecc-step-size

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Date:   Mon, 20 May 2019 13:51:19 -0400
From:   Kamal Dasu <kdasu.kdev@...il.com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     MTD Maling List <linux-mtd@...ts.infradead.org>,
        bcm-kernel-feedback-list@...adcom.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Brian Norris <computersforpeace@...il.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Vignesh Raghavendra <vigneshr@...com>
Subject: Re: [PATCH 2/2] mtd: nand: raw: brcmnand: fallback to detected
 ecc-strength, ecc-step-size

On Mon, May 20, 2019 at 1:34 PM Miquel Raynal <miquel.raynal@...tlin.com> wrote:
>
> Hi Kamal,
>
> Kamal Dasu <kdasu.kdev@...il.com> wrote on Mon, 20 May 2019 13:31:52
> -0400:
>
> > Will make the changes and send a V2 patch.
> >
> > On Mon, May 20, 2019 at 8:44 AM Miquel Raynal <miquel.raynal@...tlin.com> wrote:
> > >
> > > Hi Kamal,
> > >
> > > Kamal Dasu <kdasu.kdev@...il.com> wrote on Fri, 17 May 2019 14:29:55
> > > -0400:
> > >
> > > > This change supports nand-ecc-step-size and nand-ecc-strenght fields in
> > >
> > >                                                        strength
> > >
> > > > brcmnand dt node to be  optional.
> > >
> > >            DT            ^ extra space
> > >
> > > > see: Documentation/devicetree/bindings/mtd/brcm,brcmnand.txt
> > > >
> > > > If both nand-ecc-strength and nand-ecc-step-size are not specified in
> > > > device tree node for NAND, nand_base driver does detect onfi ext ecc
> > >
> > > s/nand_base driver/the raw NAND layer/
> > > s/onfi/ONFI/
> > > s/ecc/ECC/
> > >
> > > What is "ext"? Please use plain English here.
> > >
> > > > info from ONFI extended parameter page for parts using ONFI >= 2.1. In
> > >
> > > s/info/information/
> > >
> > > > case of non-onfi NAND there could be a nand_id table entry with the ecc
> > >
> > > s/ecc/ECC/
> > >
> > > > info. If there is a valid  device tree entry for nand-ecc-strength and
> > > > nand-ecc-step-size fields it still shall override the detected values.
> > > >
> > > > Signed-off-by: Kamal Dasu <kdasu.kdev@...il.com>
> > > > ---
> > > >  drivers/mtd/nand/raw/brcmnand/brcmnand.c | 10 ++++++++++
> > > >  1 file changed, 10 insertions(+)
> > > >
> > > > diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> > > > index ce0b8ff..e967b30 100644
> > > > --- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> > > > +++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> > > > @@ -2144,6 +2144,16 @@ static int brcmnand_setup_dev(struct brcmnand_host *host)
> > > >               return -EINVAL;
> > > >       }
> > > >
> > > > +     if (!(chip->ecc.size > 0 && chip->ecc.strength > 0) &&
> > >
> > > Is the case where only size OR strength is valid handled?
> >
> > Both strength and need to be valid, else the driver will behave like
> > before and will fail the probe.
>
> Yes, but you do not handle the case when either strength OR size is not
> valid but the other one is. Is it one purpose?
>

If I understand you want me to use the following check:

if (ecc->mode != NAND_ECC_NONE && (!ecc->size || !ecc->strength)) {
if (chip->base.eccreq.step_size && chip->base.eccreq.strength) {
     /* use the base values */
}

> >
> > >
> > > > +         (chip->base.eccreq.strength > 0 &&
> > > > +          chip->base.eccreq.step_size > 0)) {
> > > > +             /* use detected ecc parameters */
> > >
> > >                    Use          ECC
> > >
> > > > +             chip->ecc.size = chip->base.eccreq.step_size;
> > > > +             chip->ecc.strength = chip->base.eccreq.strength;
> > > > +             pr_info("Using detected nand-ecc-step-size %d, nand-ecc-strength %d\n",
> > > > +                     chip->ecc.size, chip->ecc.strength);
> > > > +     }
> > > > +
> > > >       switch (chip->ecc.size) {
> > > >       case 512:
> > > >               if (chip->ecc.algo == NAND_ECC_HAMMING)
> > >
> > >
> > > Thanks,
> > > Miquèl
> >
> > Kamal
>
>
>
>
> Thanks,
> Miquèl

Kamal