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Commit dbc44edb authored by Boris Brezillon's avatar Boris Brezillon Committed by Miquel Raynal
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mtd: rawnand: micron: Fix on-die ECC detection logic 



Basing the "mandatory on-die" detection on ID byte 2 does not work,
because Micron has plenty of NANDs using the same device ID code, and
not all of them have forcibly enabled on-die ECC.

Since the "Array Operation" feature does not provide the "ECC
enabled/disabled" bit when the ECC can't be disabled, let's try to use
the "ECC enabled/disabled" bit in the READ_ID bytes.

It seems that this bit is dynamically updated on NANDs where on-die ECC
can freely be enabled/disabled, so let's hope it stays at one when we
have a NAND with on-die ECC forcibly enabled.

Fixes: 51f3b3970a8c ("mtd: rawnand: micron: detect forced on-die ECC")
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@bootlin.com>
Tested-by: default avatarChris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
parent 79e1ca37

drivers/mtd/nand/raw/nand_micron.c

+23 −9
Original line number Diff line number Diff line
@@ -196,6 +196,9 @@ enum { 
	MICRON_ON_DIE_MANDATORY,

};



#define MICRON_ID_INTERNAL_ECC_MASK	GENMASK(1, 0)

#define MICRON_ID_ECC_ENABLED		BIT(7)



/*

 * Try to detect if the NAND support on-die ECC. To do this, we enable

 * the feature, and read back if it has been enabled as expected. We
@@ -208,7 +211,7 @@ enum { 
 */

static int micron_supports_on_die_ecc(struct nand_chip *chip)

{

	u8 feature[ONFI_SUBFEATURE_PARAM_LEN] = { 0, };

	u8 id[5];

	int ret;



	if (!chip->parameters.onfi.version)
@@ -217,26 +220,37 @@ static int micron_supports_on_die_ecc(struct nand_chip *chip) 
	if (chip->bits_per_cell != 1)

		return MICRON_ON_DIE_UNSUPPORTED;



	/*

	 * We only support on-die ECC of 4/512 or 8/512

	 */

	if  (chip->ecc_strength_ds != 4 && chip->ecc_strength_ds != 8)

		return MICRON_ON_DIE_UNSUPPORTED;



	/* 0x2 means on-die ECC is available. */

	if (chip->id.len != 5 ||

	    (chip->id.data[4] & MICRON_ID_INTERNAL_ECC_MASK) != 0x2)

		return MICRON_ON_DIE_UNSUPPORTED;



	ret = micron_nand_on_die_ecc_setup(chip, true);

	if (ret)

		return MICRON_ON_DIE_UNSUPPORTED;



	ret = nand_get_features(chip, ONFI_FEATURE_ON_DIE_ECC, feature);

	if (ret < 0)

		return ret;

	ret = nand_readid_op(chip, 0, id, sizeof(id));

	if (ret)

		return MICRON_ON_DIE_UNSUPPORTED;



	if ((feature[0] & ONFI_FEATURE_ON_DIE_ECC_EN) == 0)

	if (!(id[4] & MICRON_ID_ECC_ENABLED))

		return MICRON_ON_DIE_UNSUPPORTED;



	ret = micron_nand_on_die_ecc_setup(chip, false);

	if (ret)

		return MICRON_ON_DIE_UNSUPPORTED;



	ret = nand_get_features(chip, ONFI_FEATURE_ON_DIE_ECC, feature);

	if (ret < 0)

		return ret;

	ret = nand_readid_op(chip, 0, id, sizeof(id));

	if (ret)

		return MICRON_ON_DIE_UNSUPPORTED;



	if (feature[0] & ONFI_FEATURE_ON_DIE_ECC_EN)

	if (id[4] & MICRON_ID_ECC_ENABLED)

		return MICRON_ON_DIE_MANDATORY;



	/*