From e237285113963bd1dd2e925770aa8b3aa8a1894c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Micha=C5=82=20K=C4=99pie=C5=84?= Date: Wed, 29 Jun 2022 14:57:34 +0200 Subject: [PATCH 1/4] mtd: track maximum number of bitflips for each read request MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit mtd_read_oob() callers are currently oblivious to the details of ECC errors detected during the read operation - they only learn (through the return value) whether any corrected bitflips or uncorrectable errors occurred. More detailed ECC information can be useful to user-space applications for making better-informed choices about moving data around. Extend struct mtd_oob_ops with a pointer to a newly-introduced struct mtd_req_stats and set its 'max_bitflips' field to the maximum number of bitflips found in a single ECC step during the read operation performed by mtd_read_oob(). This is a prerequisite for ultimately passing that value back to user space. Suggested-by: Boris Brezillon Signed-off-by: Michał Kępień Signed-off-by: Miquel Raynal Link: https://lore.kernel.org/linux-mtd/20220629125737.14418-2-kernel@kempniu.pl --- drivers/mtd/mtdcore.c | 5 +++++ include/linux/mtd/mtd.h | 5 +++++ 2 files changed, 10 insertions(+) --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -1676,6 +1676,9 @@ int mtd_read_oob(struct mtd_info *mtd, l if (!master->_read_oob && (!master->_read || ops->oobbuf)) return -EOPNOTSUPP; + if (ops->stats) + memset(ops->stats, 0, sizeof(*ops->stats)); + if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) ret_code = mtd_io_emulated_slc(mtd, from, true, ops); else @@ -1693,6 +1696,8 @@ int mtd_read_oob(struct mtd_info *mtd, l return ret_code; if (mtd->ecc_strength == 0) return 0; /* device lacks ecc */ + if (ops->stats) + ops->stats->max_bitflips = ret_code; return ret_code >= mtd->bitflip_threshold ? -EUCLEAN : 0; } EXPORT_SYMBOL_GPL(mtd_read_oob); --- a/include/linux/mtd/mtd.h +++ b/include/linux/mtd/mtd.h @@ -40,6 +40,10 @@ struct mtd_erase_region_info { unsigned long *lockmap; /* If keeping bitmap of locks */ }; +struct mtd_req_stats { + unsigned int max_bitflips; +}; + /** * struct mtd_oob_ops - oob operation operands * @mode: operation mode @@ -70,6 +74,7 @@ struct mtd_oob_ops { uint32_t ooboffs; uint8_t *datbuf; uint8_t *oobbuf; + struct mtd_req_stats *stats; }; #define MTD_MAX_OOBFREE_ENTRIES_LARGE 32