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Commit 02b88eea authored by Kamal Dasu's avatar Kamal Dasu Committed by Boris Brezillon
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mtd: brcmnand: Add check for erased page bitflips 



Check for erased page bitflips in a page. And if well within
threshold return data as all 0xff. Apply sw check for controller
version < 7.2. Controller vesion >= 7.2 has hw support.

Signed-off-by: default avatarKamal Dasu <kdasu.kdev@gmail.com>
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
parent 1c7fe6b4

drivers/mtd/nand/brcmnand/brcmnand.c

+62 −0
Original line number Diff line number Diff line
@@ -1602,6 +1602,56 @@ static int brcmnand_read_by_pio(struct mtd_info *mtd, struct nand_chip *chip, 
	return ret;

}



/*

 * Check a page to see if it is erased (w/ bitflips) after an uncorrectable ECC

 * error

 *

 * Because the HW ECC signals an ECC error if an erase paged has even a single

 * bitflip, we must check each ECC error to see if it is actually an erased

 * page with bitflips, not a truly corrupted page.

 *

 * On a real error, return a negative error code (-EBADMSG for ECC error), and

 * buf will contain raw data.

 * Otherwise, buf gets filled with 0xffs and return the maximum number of

 * bitflips-per-ECC-sector to the caller.

 *

 */

static int brcmstb_nand_verify_erased_page(struct mtd_info *mtd,

		  struct nand_chip *chip, void *buf, u64 addr)

{

	int i, sas;

	void *oob = chip->oob_poi;

	int bitflips = 0;

	int page = addr >> chip->page_shift;

	int ret;



	if (!buf) {

		buf = chip->buffers->databuf;

		/* Invalidate page cache */

		chip->pagebuf = -1;

	}



	sas = mtd->oobsize / chip->ecc.steps;



	/* read without ecc for verification */

	chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);

	ret = chip->ecc.read_page_raw(mtd, chip, buf, true, page);

	if (ret)

		return ret;



	for (i = 0; i < chip->ecc.steps; i++, oob += sas) {

		ret = nand_check_erased_ecc_chunk(buf, chip->ecc.size,

						  oob, sas, NULL, 0,

						  chip->ecc.strength);

		if (ret < 0)

			return ret;



		bitflips = max(bitflips, ret);

	}



	return bitflips;

}



static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,

			 u64 addr, unsigned int trans, u32 *buf, u8 *oob)

{
@@ -1632,6 +1682,18 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip, 
	}



	if (mtd_is_eccerr(err)) {

		/*

		 * Controller version 7.2 has hw encoder to detect erased page

		 * bitflips, apply sw verification for older controllers only

		 */

		if (ctrl->nand_version < 0x0702) {

			err = brcmstb_nand_verify_erased_page(mtd, chip, buf,

							      addr);

			/* erased page bitflips corrected */

			if (err > 0)

				return err;

		}



		dev_dbg(ctrl->dev, "uncorrectable error at 0x%llx\n",

			(unsigned long long)err_addr);

		mtd->ecc_stats.failed++;