| Message ID | 20200504140903.23602-4-peng.fan@nxp.com |
|---|---|
| State | Accepted |
| Commit | 552c88273ef9c5ebe269d47e7610a39ef5bfa5cc |
| Headers | show |
| Series | mtd: nand: i.MX update | expand |
> This patch is porting from linux: > http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/commit/ > ?h=imx_4.1.15_1.0.0_ga&id=3d42fcece496224fde59f9343763fb2dfc5b0768 > " > We may meet the bitflips in reading an erased page(contains all 0xFF), > this may causes the UBIFS corrupt, please see the log from Elie: > ----------------------------------------------------------------- > [ 3.831323] UBI warning: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read only 16384 bytes, retry > [ 3.845026] UBI warning: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read only 16384 bytes, retry > [ 3.858710] UBI warning: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read only 16384 bytes, retry > [ 3.872408] UBI error: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read 16384 bytes > ... > [ 4.011529] UBIFS error (pid 36): ubifs_recover_leb: corrupt empty space LEB 27:237568, corruption starts at 9815 > [ 4.021897] UBIFS error (pid 36): ubifs_scanned_corruption: corruption at LEB 27:247383 > [ 4.030000] UBIFS error (pid 36): ubifs_scanned_corruption: first 6569 bytes from LEB 27:247383 > ----------------------------------------------------------------- > This patch does a check for the uncorrectable failure in the following steps: > [0] set the threshold. > The threshold is set based on the truth: > "A single 0 bit will lead to gf_len(13 or 14) bits 0 after the BCH > do the ECC." > For the sake of safe, we will set the threshold with half the gf_len, and > do not make it bigger the ECC strength. > [1] count the bitflips of the current ECC chunk, assume it is N. > [2] if the (N <= threshold) is true, we continue to read out the page with > ECC disabled. and we count the bitflips again, assume it is N2. > (We read out the whole page, not just a chunk, this makes the check > more strictly, and make the code more simple.) > [3] if the (N2 <= threshold) is true again, we can regard this is a erased > page. This is because a real erased page is full of 0xFF(maybe also has > several bitflips), while a page contains the 0xFF data will definitely > has many bitflips in the ECC parity areas. > [4] if the [3] fails, we can regard this is a page filled with the '0xFF' > data. > " > Signed-off-by: Peng Fan <peng.fan at nxp.com> Applied to u-boot-imx, master, thanks ! Best regards, Stefano Babic
diff --git a/drivers/mtd/nand/raw/mxs_nand.c b/drivers/mtd/nand/raw/mxs_nand.c index 3247064c3f..55d24cd062 100644 --- a/drivers/mtd/nand/raw/mxs_nand.c +++ b/drivers/mtd/nand/raw/mxs_nand.c @@ -612,6 +612,45 @@ static uint8_t mxs_nand_read_byte(struct mtd_info *mtd) return buf; } +static bool mxs_nand_erased_page(struct mtd_info *mtd, struct nand_chip *nand, + u8 *buf, int chunk, int page) +{ + struct mxs_nand_info *nand_info = nand_get_controller_data(nand); + struct bch_geometry *geo = &nand_info->bch_geometry; + unsigned int flip_bits = 0, flip_bits_noecc = 0; + unsigned int threshold; + unsigned int base = geo->ecc_chunkn_size * chunk; + u32 *dma_buf = (u32 *)buf; + int i; + + threshold = geo->gf_len / 2; + if (threshold > geo->ecc_strength) + threshold = geo->ecc_strength; + + for (i = 0; i < geo->ecc_chunkn_size; i++) { + flip_bits += hweight8(~buf[base + i]); + if (flip_bits > threshold) + return false; + } + + nand->cmdfunc(mtd, NAND_CMD_READ0, 0, page); + nand->read_buf(mtd, buf, mtd->writesize); + + for (i = 0; i < mtd->writesize / 4; i++) { + flip_bits_noecc += hweight32(~dma_buf[i]); + if (flip_bits_noecc > threshold) + return false; + } + + mtd->ecc_stats.corrected += flip_bits; + + memset(buf, 0xff, mtd->writesize); + + printf("The page(%d) is an erased page(%d,%d,%d,%d).\n", page, chunk, threshold, flip_bits, flip_bits_noecc); + + return true; +} + /* * Read a page from NAND. */ @@ -715,6 +754,8 @@ static int mxs_nand_ecc_read_page(struct mtd_info *mtd, struct nand_chip *nand, goto rtn; } + mxs_nand_return_dma_descs(nand_info); + /* Invalidate caches */ mxs_nand_inval_data_buf(nand_info); @@ -731,6 +772,9 @@ static int mxs_nand_ecc_read_page(struct mtd_info *mtd, struct nand_chip *nand, continue; if (status[i] == 0xfe) { + if (mxs_nand_erased_page(mtd, nand, + nand_info->data_buf, i, page)) + break; failed++; continue; }
This patch is porting from linux: http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/commit/ ?h=imx_4.1.15_1.0.0_ga&id=3d42fcece496224fde59f9343763fb2dfc5b0768 " We may meet the bitflips in reading an erased page(contains all 0xFF), this may causes the UBIFS corrupt, please see the log from Elie: ----------------------------------------------------------------- [ 3.831323] UBI warning: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read only 16384 bytes, retry [ 3.845026] UBI warning: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read only 16384 bytes, retry [ 3.858710] UBI warning: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read only 16384 bytes, retry [ 3.872408] UBI error: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read 16384 bytes ... [ 4.011529] UBIFS error (pid 36): ubifs_recover_leb: corrupt empty space LEB 27:237568, corruption starts at 9815 [ 4.021897] UBIFS error (pid 36): ubifs_scanned_corruption: corruption at LEB 27:247383 [ 4.030000] UBIFS error (pid 36): ubifs_scanned_corruption: first 6569 bytes from LEB 27:247383 ----------------------------------------------------------------- This patch does a check for the uncorrectable failure in the following steps: [0] set the threshold. The threshold is set based on the truth: "A single 0 bit will lead to gf_len(13 or 14) bits 0 after the BCH do the ECC." For the sake of safe, we will set the threshold with half the gf_len, and do not make it bigger the ECC strength. [1] count the bitflips of the current ECC chunk, assume it is N. [2] if the (N <= threshold) is true, we continue to read out the page with ECC disabled. and we count the bitflips again, assume it is N2. (We read out the whole page, not just a chunk, this makes the check more strictly, and make the code more simple.) [3] if the (N2 <= threshold) is true again, we can regard this is a erased page. This is because a real erased page is full of 0xFF(maybe also has several bitflips), while a page contains the 0xFF data will definitely has many bitflips in the ECC parity areas. [4] if the [3] fails, we can regard this is a page filled with the '0xFF' data. " Signed-off-by: Peng Fan <peng.fan at nxp.com> --- drivers/mtd/nand/raw/mxs_nand.c | 44 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+)