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mtd: rawnand: micron: Fix on-die ECC detection logic

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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: Boris Brezillon <boris.brezillon@bootlin.com>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
This commit is contained in:
Boris Brezillon 2018-07-18 10:42:15 +02:00 committed by Miquel Raynal
parent 79e1ca37cc
commit dbc44edbf8
1 changed files with 23 additions and 9 deletions
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32
drivers/mtd/nand/raw/nand_micron.c
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@ -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;
/*