Messages in this thread Patch in this message | | | Date | Sat, 26 May 2018 10:42:47 +0200 | From | Miquel Raynal <> | Subject | Re: [PATCH v3 01/16] mtd: rawnand: helper function for setting up ECC configuration |
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Hi Abhishek,
On Fri, 25 May 2018 17:51:29 +0530, Abhishek Sahu <absahu@codeaurora.org> wrote:
> commit 2c8f8afa7f92 ("mtd: nand: add generic helpers to check, > match, maximize ECC settings") provides generic helpers which > drivers can use for setting up ECC parameters. > > Since same board can have different ECC strength nand chips so > following is the logic for setting up ECC strength and ECC step > size, which can be used by most of the drivers. > > 1. If both ECC step size and ECC strength are already set > (usually by DT) then just check whether this setting > is supported by NAND controller. > 2. If NAND_ECC_MAXIMIZE is set, then select maximum ECC strength > supported by NAND controller. > 3. Otherwise, try to match the ECC step size and ECC strength closest > to the chip's requirement. If available OOB size can't fit the chip > requirement then select maximum ECC strength which can be fit with > available OOB size. > > This patch introduces nand_ecc_choose_conf function which calls the > required helper functions for the above logic. The drivers can use > this single function instead of calling the 3 helper functions > individually. > > CC: Masahiro Yamada <yamada.masahiro@socionext.com> > Signed-off-by: Abhishek Sahu <absahu@codeaurora.org> > --- > * Changes from v2: > > 1. Renamed function to nand_ecc_choose_conf. > 2. Minor code reorganization to remove warning and 2 function calls > for nand_maximize_ecc. > > * Changes from v1: > NEW PATCH > > drivers/mtd/nand/raw/nand_base.c | 42 ++++++++++++++++++++++++++++++++++++++++ > drivers/mtd/nand/raw/nand_base.c | 31 +++++++++++++++++++++++++++++++ > include/linux/mtd/rawnand.h | 3 +++ > 2 files changed, 34 insertions(+) > > diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c > index 72f3a89..e52019d 100644 > --- a/drivers/mtd/nand/raw/nand_base.c > +++ b/drivers/mtd/nand/raw/nand_base.c > @@ -6249,6 +6249,37 @@ int nand_maximize_ecc(struct nand_chip *chip, > } > EXPORT_SYMBOL_GPL(nand_maximize_ecc); > > +/** > + * nand_ecc_choose_conf - Set the ECC strength and ECC step size > + * @chip: nand chip info structure > + * @caps: ECC engine caps info structure > + * @oobavail: OOB size that the ECC engine can use > + * > + * Choose the ECC configuration according to following logic > + * > + * 1. If both ECC step size and ECC strength are already set (usually by DT) > + * then check if it is supported by this controller. > + * 2. If NAND_ECC_MAXIMIZE is set, then select maximum ECC strength. > + * 3. Otherwise, try to match the ECC step size and ECC strength closest > + * to the chip's requirement. If available OOB size can't fit the chip > + * requirement then fallback to the maximum ECC step size and ECC strength. > + * > + * On success, the chosen ECC settings are set. > + */ > +int nand_ecc_choose_conf(struct nand_chip *chip, > + const struct nand_ecc_caps *caps, int oobavail) > +{ > + if (chip->ecc.size && chip->ecc.strength) > + return nand_check_ecc_caps(chip, caps, oobavail); > + > + if (!(chip->ecc.options & NAND_ECC_MAXIMIZE) && > + !nand_match_ecc_req(chip, caps, oobavail)) > + return 0; > + > + return nand_maximize_ecc(chip, caps, oobavail);
I personally don't mind if nand_maximize_ecc() is called twice in the function if it clarifies the logic. Maybe the following will be more clear for the user?
if (chip->ecc.size && chip->ecc.strength) return nand_check_ecc_caps(chip, caps, oobavail);
if (chip->ecc.options & NAND_ECC_MAXIMIZE) return nand_maximize_ecc(chip, caps, oobavail);
if (!nand_match_ecc_req(chip, caps, oobavail)) return 0;
return nand_maximize_ecc(chip, caps, oobavail);
Also, I'm not sure we should just error out when nand_check_ecc_caps() fails. What about something more robust, like:
int ret;
if (chip->ecc.size && chip->ecc.strength) { ret = nand_check_ecc_caps(chip, caps, oobavail); if (ret) goto maximize_ecc;
return 0; }
if (chip->ecc.options & NAND_ECC_MAXIMIZE) goto maximize_ecc;
ret = nand_match_ecc_req(chip, caps, oobavail); if (ret) goto maximize_ecc;
return 0;
maximize_ecc: return nand_maximize_ecc(chip, caps, oobavail);
> +} > +EXPORT_SYMBOL_GPL(nand_ecc_choose_conf); > + > /* > * Check if the chip configuration meet the datasheet requirements. > > diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h > index 5dad59b..89889fa 100644 > --- a/include/linux/mtd/rawnand.h > +++ b/include/linux/mtd/rawnand.h > @@ -1627,6 +1627,9 @@ int nand_match_ecc_req(struct nand_chip *chip, > int nand_maximize_ecc(struct nand_chip *chip, > const struct nand_ecc_caps *caps, int oobavail); > > +int nand_ecc_choose_conf(struct nand_chip *chip, > + const struct nand_ecc_caps *caps, int oobavail); > + > /* Default write_oob implementation */ > int nand_write_oob_std(struct mtd_info *mtd, struct nand_chip *chip, int page); >
Thanks, Miquèl
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