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From:   zdhays@gmail.com
Cc:     zhays@lexmark.com, Zak Hays <zdhays@gmail.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Frieder Schrempf <frieder.schrempf@kontron.de>,
        Boris Brezillon <bbrezillon@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Piotr Sroka <piotrs@cadence.com>,
        Marco Felsch <m.felsch@pengutronix.de>,
        linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH v1] mtd: rawnand: micron: don't error out if internal ECC is set
Date:   Fri, 10 Jan 2020 11:25:01 -0500
Message-Id: <20200110162503.7185-1-zdhays@gmail.com>
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Sender: linux-kernel-owner@vger.kernel.org
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From: Zak Hays <zdhays@gmail.com>

Recent changes to the driver require use of on-die correction if
the internal ECC enable bit is set. On some Micron parts, this bit
is enabled by default and there is no method for disabling it.

This is a false assumption though as that bit being enabled does not
necessarily mean that the on-die ECC *has* to be used. It has been
verified with a Micron FAE that other methods of error correction are
still valid even if this bit is set.

HW ECC offers generally higher performance than on-die so it is
preferred in some situations. This also allows multiple NAND parts to
be supported on the same PCB as some parts may not support on-die
error correction.

With that in mind, only throw a warning that the on-die bit is set
and allow the init to continue.

Signed-off-by: Zak Hays <zdhays@gmail.com>
---
 drivers/mtd/nand/raw/nand_micron.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_micron.c b/drivers/mtd/nand/raw/nand_micron.c
index 56654030ec7f..ec40c76443be 100644
--- a/drivers/mtd/nand/raw/nand_micron.c
+++ b/drivers/mtd/nand/raw/nand_micron.c
@@ -455,9 +455,7 @@ static int micron_nand_init(struct nand_chip *chip)
 
 	if (ondie == MICRON_ON_DIE_MANDATORY &&
 	    chip->ecc.mode != NAND_ECC_ON_DIE) {
-		pr_err("On-die ECC forcefully enabled, not supported\n");
-		ret = -EINVAL;
-		goto err_free_manuf_data;
+		pr_warn("WARNING: On-die ECC forcefully enabled, use caution with other methods\n");
 	}
 
 	if (chip->ecc.mode == NAND_ECC_ON_DIE) {
-- 
2.17.1