From afc0ea1b8e1e27b2cb77e7023d917f3aa5971d17 Mon Sep 17 00:00:00 2001 From: Roger Quadros Date: Tue, 21 Oct 2014 16:53:28 +0300 Subject: mtd: mtd_oobtest: add bitflip_limit parameter It is common for NAND devices to have bitflip errors. Add a bitflip_limit parameter to specify how many bitflips per page we can tolerate without flagging an error. By default zero bitflips are tolerated. Signed-off-by: Roger Quadros Signed-off-by: Sekhar Nori Signed-off-by: Brian Norris --- drivers/mtd/tests/oobtest.c | 65 ++++++++++++++++++++++++++++++++------------- 1 file changed, 47 insertions(+), 18 deletions(-) (limited to 'drivers/mtd/tests') diff --git a/drivers/mtd/tests/oobtest.c b/drivers/mtd/tests/oobtest.c index edd859d96d85..1fd2cdad85f0 100644 --- a/drivers/mtd/tests/oobtest.c +++ b/drivers/mtd/tests/oobtest.c @@ -34,8 +34,11 @@ #include "mtd_test.h" static int dev = -EINVAL; +static int bitflip_limit; module_param(dev, int, S_IRUGO); MODULE_PARM_DESC(dev, "MTD device number to use"); +module_param(bitflip_limit, int, S_IRUGO); +MODULE_PARM_DESC(bitflip_limit, "Max. allowed bitflips per page"); static struct mtd_info *mtd; static unsigned char *readbuf; @@ -115,24 +118,27 @@ static int write_whole_device(void) return 0; } -/* Display the address, offset and data bytes at comparison failure */ -static int memcmpshow(loff_t addr, const void *cs, const void *ct, size_t count) +/* + * Display the address, offset and data bytes at comparison failure. + * Return number of bitflips encountered. + */ +static size_t memcmpshow(loff_t addr, const void *cs, const void *ct, size_t count) { const unsigned char *su1, *su2; int res; - int ret = 0; size_t i = 0; + size_t bitflips = 0; for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--, i++) { res = *su1 ^ *su2; if (res) { pr_info("error @addr[0x%lx:0x%x] 0x%x -> 0x%x diff 0x%x\n", (unsigned long)addr, i, *su1, *su2, res); - ret = 1; + bitflips += hweight8(res); } } - return ret; + return bitflips; } static int verify_eraseblock(int ebnum) @@ -141,6 +147,7 @@ static int verify_eraseblock(int ebnum) struct mtd_oob_ops ops; int err = 0; loff_t addr = (loff_t)ebnum * mtd->erasesize; + size_t bitflips; prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt); for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) { @@ -159,9 +166,11 @@ static int verify_eraseblock(int ebnum) errcnt += 1; return err ? err : -1; } - if (memcmpshow(addr, readbuf, - writebuf + (use_len_max * i) + use_offset, - use_len)) { + + bitflips = memcmpshow(addr, readbuf, + writebuf + (use_len_max * i) + use_offset, + use_len); + if (bitflips > bitflip_limit) { pr_err("error: verify failed at %#llx\n", (long long)addr); errcnt += 1; @@ -169,7 +178,10 @@ static int verify_eraseblock(int ebnum) pr_err("error: too many errors\n"); return -1; } + } else if (bitflips) { + pr_info("ignoring error as within bitflip_limit\n"); } + if (use_offset != 0 || use_len < mtd->ecclayout->oobavail) { int k; @@ -188,9 +200,10 @@ static int verify_eraseblock(int ebnum) errcnt += 1; return err ? err : -1; } - if (memcmpshow(addr, readbuf + use_offset, - writebuf + (use_len_max * i) + use_offset, - use_len)) { + bitflips = memcmpshow(addr, readbuf + use_offset, + writebuf + (use_len_max * i) + use_offset, + use_len); + if (bitflips > bitflip_limit) { pr_err("error: verify failed at %#llx\n", (long long)addr); errcnt += 1; @@ -198,7 +211,10 @@ static int verify_eraseblock(int ebnum) pr_err("error: too many errors\n"); return -1; } + } else if (bitflips) { + pr_info("ignoring error as within bitflip_limit\n"); } + for (k = 0; k < use_offset; ++k) if (readbuf[k] != 0xff) { pr_err("error: verify 0xff " @@ -237,6 +253,9 @@ static int verify_eraseblock_in_one_go(int ebnum) int err = 0; loff_t addr = (loff_t)ebnum * mtd->erasesize; size_t len = mtd->ecclayout->oobavail * pgcnt; + size_t oobavail = mtd->ecclayout->oobavail; + size_t bitflips; + int i; prandom_bytes_state(&rnd_state, writebuf, len); ops.mode = MTD_OPS_AUTO_OOB; @@ -247,6 +266,8 @@ static int verify_eraseblock_in_one_go(int ebnum) ops.ooboffs = 0; ops.datbuf = NULL; ops.oobbuf = readbuf; + + /* read entire block's OOB at one go */ err = mtd_read_oob(mtd, addr, &ops); if (err || ops.oobretlen != len) { pr_err("error: readoob failed at %#llx\n", @@ -254,13 +275,21 @@ static int verify_eraseblock_in_one_go(int ebnum) errcnt += 1; return err ? err : -1; } - if (memcmpshow(addr, readbuf, writebuf, len)) { - pr_err("error: verify failed at %#llx\n", - (long long)addr); - errcnt += 1; - if (errcnt > 1000) { - pr_err("error: too many errors\n"); - return -1; + + /* verify one page OOB at a time for bitflip per page limit check */ + for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) { + bitflips = memcmpshow(addr, readbuf + (i * oobavail), + writebuf + (i * oobavail), oobavail); + if (bitflips > bitflip_limit) { + pr_err("error: verify failed at %#llx\n", + (long long)addr); + errcnt += 1; + if (errcnt > 1000) { + pr_err("error: too many errors\n"); + return -1; + } + } else if (bitflips) { + pr_info("ignoring error as within bitflip_limit\n"); } } -- cgit