From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qy0-f177.google.com ([209.85.216.177]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1RYOjc-00061P-4Z for linux-mtd@lists.infradead.org; Wed, 07 Dec 2011 21:09:00 +0000 Received: by qcsf1 with SMTP id f1so914519qcs.36 for ; Wed, 07 Dec 2011 13:08:58 -0800 (PST) From: Brian Norris To: Artem Bityutskiy Subject: [PATCH] mtd: nand: write bad block marker even with BBT Date: Wed, 7 Dec 2011 13:08:20 -0800 Message-Id: <1323292100-19280-1-git-send-email-computersforpeace@gmail.com> Cc: Jim Quinlan , Kevin Cernekee , Brian Norris , linux-mtd@lists.infradead.org, Matthieu CASTET List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Add and option (NAND_BBT_WRITE_BBM) for writing bad block markers to proper OOB area on each block in addition to flash-based BBT. This is useful when: * bootloader cannot read the flash-based BBT format * BBT is corrupted and the flash must be rescanned for bad blocks; we want to remember bad blocks that were marked from Linux Adapted from code by Matthieu CASTET. Cc: Matthieu CASTET Signed-off-by: Brian Norris --- Last year's discussion thread: http://lists.infradead.org/pipermail/linux-mtd/2010-October/032942.html I'll address the criticisms: "add a BUG_ON to catch misuse cases when NAND_WRITE_BB [now named NAND_BBT_WRITE_BBM] is used without NAND_USE_FLASH_BBT - they should go in pair" NAND_BBT_WRITE_BBM has no special effect when used without NAND_BBT_USE_FLASH; it's already the default behavior. So I don't expect it to be an issue. "And also, how about cases when BBT is updated, but OOB did not because of a power cut" Not a very likely case as bad blocks are written infrequently, plus for the situations where we're writing BBM simply because the bootloader doesn't understand our BBT, having 99% of blocks marked properly is better than none. drivers/mtd/nand/nand_base.c | 11 +++++++++-- include/linux/mtd/bbm.h | 9 +++++++++ 2 files changed, 18 insertions(+), 2 deletions(-) diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index 35b4565..6d619f7 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -392,7 +392,7 @@ static int nand_default_block_markbad(struct mtd_info *mtd, loff_t ofs) { struct nand_chip *chip = mtd->priv; uint8_t buf[2] = { 0, 0 }; - int block, ret, i = 0; + int block, ret = 0, i = 0; if (chip->bbt_options & NAND_BBT_SCANLASTPAGE) ofs += mtd->erasesize - mtd->writesize; @@ -405,7 +405,14 @@ static int nand_default_block_markbad(struct mtd_info *mtd, loff_t ofs) /* Do we have a flash based bad block table? */ if (chip->bbt_options & NAND_BBT_USE_FLASH) ret = nand_update_bbt(mtd, ofs); - else { + /* + * Write bad block marker to OOB, in one of two cases: + * (1) we don't have flash-based BBT + * (2) we have flash-based BBT but also want to keep markers in OOB in + * each block + */ + if (!(chip->bbt_options & NAND_BBT_USE_FLASH) || + (chip->bbt_options & NAND_BBT_WRITE_BBM)) { struct mtd_oob_ops ops; nand_get_device(chip, mtd, FL_WRITING); diff --git a/include/linux/mtd/bbm.h b/include/linux/mtd/bbm.h index c4eec22..61fcb30 100644 --- a/include/linux/mtd/bbm.h +++ b/include/linux/mtd/bbm.h @@ -112,6 +112,15 @@ struct nand_bbt_descr { #define NAND_BBT_USE_FLASH 0x00020000 /* Do not store flash based bad block table in OOB area; store it in-band */ #define NAND_BBT_NO_OOB 0x00040000 +/* + * Write bad block marker to OOB when marking new bad blocks. This is the + * default behavior without NAND_USE_FLASH_BBT, so this is only useful in + * conjunction with NAND_USE_FLASH_BBT. + * One might need bad blocks marked in each block as well as in BBT when + * bootloader cannot read the flash-based BBT format or when the BBT is + * corrupted and the flash must be rescanned for bad blocks. + */ +#define NAND_BBT_WRITE_BBM 0x00080000 /* * Flag set by nand_create_default_bbt_descr(), marking that the nand_bbt_descr -- 1.7.5.4