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Commit 13fbe064 authored by Pekon Gupta's avatar Pekon Gupta Committed by Brian Norris
Browse files

mtd: nand: omap: ecc.correct: omap_elm_correct_data: fix programmed-page bit-flip correction logic 



This patch updates following checks when bit-flips are detected by ELM:

 - Do not evaluate bit-flips when un-correctable bit-flips is reported by ELM,
   because as per [1] when ELM reports an un-correctable bit-flips,
   'number of error' field in its ELM_LOCATION_STATUS register is also invalid.

 - Return with error-code '-EBADMSG' on detection of un-correctable bit-flip.

 - Return with error-code '-EBADMSG' when bit-flips position is outside current
   Sector and OOB area.

[1] ELM IP spec Table-25 ELM_LOCATION_STATUS Register.
    ELM_LOCATION_STATUS[8] = ECC_CORRECTABLE: Error location process exit status
        0x0: ECC error location process failed.
             Number of errors and error locations are invalid.
        0x1: all errors were successfully located.
             Number of errors and error locations are valid.

Tested-by: default avatarStefan Roese <sr@denx.de>
Signed-off-by: default avatarPekon Gupta <pekon@ti.com>
Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
parent b08e1f63

drivers/mtd/nand/omap2.c

+19 −10
Original line number Diff line number Diff line
@@ -1353,6 +1353,7 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data, 
	int bitflip_count;

	bool is_error_reported = false;

	u32 bit_pos, byte_pos, error_max, pos;

	int err;



	switch (info->ecc_opt) {

	case OMAP_ECC_BCH4_CODE_HW:
@@ -1434,8 +1435,12 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data, 
	/* Decode BCH error using ELM module */

	elm_decode_bch_error_page(info->elm_dev, ecc_vec, err_vec);



	err = 0;

	for (i = 0; i < eccsteps; i++) {

		if (err_vec[i].error_reported) {

		if (err_vec[i].error_uncorrectable) {

			pr_err("nand: uncorrectable bit-flips found\n");

			err = -EBADMSG;

		} else if (err_vec[i].error_reported) {

			for (j = 0; j < err_vec[i].error_count; j++) {

				switch (info->ecc_opt) {

				case OMAP_ECC_BCH4_CODE_HW:
@@ -1457,13 +1462,22 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data, 
				byte_pos = (error_max - pos - 1) / 8;



				if (pos < error_max) {

					if (byte_pos < 512)

					if (byte_pos < 512) {

						pr_debug("bitflip@dat[%d]=%x\n",

						     byte_pos, data[byte_pos]);

						data[byte_pos] ^= 1 << bit_pos;

					else

					} else {

						pr_debug("bitflip@oob[%d]=%x\n",

							(byte_pos - 512),

						     spare_ecc[byte_pos - 512]);

						spare_ecc[byte_pos - 512] ^=

							1 << bit_pos;

					}

				/* else, not interested to correct ecc */

				} else {

					pr_err("invalid bit-flip @ %d:%d\n",

							 byte_pos, bit_pos);

					err = -EBADMSG;

				}

			}

		}
@@ -1475,12 +1489,7 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data, 
		spare_ecc += ecc->bytes;

	}



	for (i = 0; i < eccsteps; i++)

		/* Return error if uncorrectable error present */

		if (err_vec[i].error_uncorrectable)

			return -EINVAL;



	return stat;

	return (err) ? err : stat;

}



/**