Messages in this thread | | | Subject | Re: [PATCH -next] mtd: nand: Add support for Toshiba BENAND (Built-in ECC NAND) | From | KOBAYASHI Yoshitake <> | Date | Wed, 7 Jun 2017 17:17:29 +0900 |
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On 2017/06/07 6:11, Boris Brezillon wrote: > On Mon, 5 Jun 2017 14:36:23 +0900 > KOBAYASHI Yoshitake <yoshitake.kobayashi@toshiba.co.jp> wrote: > >> Hi Boris, >> >> Thank you very much for your detailed review. >> I just comming back from busy week for conference and started to look it. >> >> I have a question regarding to the following comment. >> >>>> static int toshiba_nand_init(struct nand_chip *chip) >>>> { >>>> + struct mtd_info *mtd = nand_to_mtd(chip); >>>> + >>>> if (nand_is_slc(chip)) >>>> chip->bbt_options |= NAND_BBT_SCAN2NDPAGE; >>>> >>>> + if (chip->ecc.mode == NAND_ECC_BENAND) { >>>> + chip->ecc.options = NAND_ECC_CUSTOM_PAGE_ACCESS; >>>> + chip->ecc.bytes = 0; >>> >>> It should be set to 16 according to the datasheet. But I guess this is >>> not exactly true. I'm pretty sure we can use some of these bytes to >>> store real data. Assuming you're using BCH, only 13bytes are needed for >>> 8bits/512bytes strength, and I guess the BBM region is also left >>> untouched (first 2 bytes of the OOB region). >> >> On BENAND, all OOB reginon can be used by user (driver). The calculated >> ECC data stored into other isolated area which is ubable to access from user. >> This is why chip->ecc.bytes = 0. > > Oh, nice! > >> To make sure this specification, I also checked the BENAND datasheet >> but unfortunatelly it was undocumented. Sorry for this confusion. > > No problem. Do you think you can update the datasheet (or ask someone > who can) to clarify this aspect? As you said, it's really not clear > that these ECC bytes are actually stored in a dedicated region that is > invisible to users.
Thank you for your comment. I asked to the product department about this. They say they are confirming whether they can update our product datasheet or not.
-- Yoshi
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