mtd: rawnand: micron: Fix support for on-die ECC

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=630691850131bc3b8cc13fd9b9c6eedb4eb64ad4
Commit:     630691850131bc3b8cc13fd9b9c6eedb4eb64ad4
Parent:     a2ee41fd953e7c3ff6c55a3038c80354d191a318
Author:     Boris Brezillon <boris.brezillon at bootlin.com>
AuthorDate: Thu May 3 09:49:08 2018 +0200
Committer:  Boris Brezillon <boris.brezillon at bootlin.com>
CommitDate: Mon May 7 09:42:55 2018 +0200

    mtd: rawnand: micron: Fix support for on-die ECC
    
    It looks like the NAND_STATUS_FAIL bit is sticky after an ECC failure,
    which leads all READ operations following the failing one to report
    an ECC failure. Reset the chip to clear the NAND_STATUS_FAIL bit.
    
    Note that this behavior is not document in the datasheet, but resetting
    the chip is the only solution we found to fix the problem.
    
    Fixes: 9748e1d87573 ("mtd: nand: add support for Micron on-die ECC")
    Cc: <stable at vger.kernel.org>
    Signed-off-by: Boris Brezillon <boris.brezillon at bootlin.com>
    Cc: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
    Cc: Bean Huo <beanhuo at micron.com>
    Cc: Peter Pan <peterpandong at micron.com>
    Reviewed-by: Miquel Raynal <miquel.raynal at bootlin.com>
---
 drivers/mtd/nand/raw/nand_micron.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/mtd/nand/raw/nand_micron.c b/drivers/mtd/nand/raw/nand_micron.c
index 0af45b134c0c..a915f568f6a3 100644
--- a/drivers/mtd/nand/raw/nand_micron.c
+++ b/drivers/mtd/nand/raw/nand_micron.c
@@ -153,6 +153,23 @@ micron_nand_read_page_on_die_ecc(struct mtd_info *mtd, struct nand_chip *chip,
 		ret = nand_read_data_op(chip, chip->oob_poi, mtd->oobsize,
 					false);
 
+	/*
+	 * Looks like the NAND_STATUS_FAIL bit is sticky after an ECC failure,
+	 * which leads all READ operations following the failing one to report
+	 * an ECC failure.
+	 * Reset the chip to clear it.
+	 *
+	 * Note that this behavior is not document in the datasheet, but
+	 * resetting the chip is the only solution we found to clear this bit.
+	 */
+	if (status & NAND_STATUS_FAIL) {
+		int cs = page >> (chip->chip_shift - chip->page_shift);
+
+		chip->select_chip(mtd, -1);
+		nand_reset(chip, cs);
+		chip->select_chip(mtd, cs);
+	}
+
 out:
 	micron_nand_on_die_ecc_setup(chip, false);