[PATCH v6 6/6] mtd: rawnand: micron: detect forced on-die ECC

[Chris Packham]

Some Micron NAND chips have on-die ECC forceably enabled. Detect these
based on chip ID as there seems to be no other way of distinguishing
these chips from those that have optional support for on-die ECC.

Signed-off-by: Chris Packham <chris.pack...@alliedtelesis.co.nz>
Reviewed-by: Boris Brezillon <boris.brezil...@bootlin.com>
---
Changes in v4:
- New
Changes in v5:
- fail if on-die ECC is mandatory and the current ecc.mode is not
  NAND_ECC_ON_DIE.
Changes in v6:
- Update commit message, add review from Boris

 drivers/mtd/nand/raw/nand_micron.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/nand_micron.c 
b/drivers/mtd/nand/raw/nand_micron.c
index f83053562925..35fa6880a799 100644
--- a/drivers/mtd/nand/raw/nand_micron.c
+++ b/drivers/mtd/nand/raw/nand_micron.c
@@ -255,6 +255,14 @@ enum {
        MICRON_ON_DIE_MANDATORY,
 };
 
+/*
+ * These parts are known to have on-die ECC forceably enabled
+ */
+static u8 micron_on_die_ecc[] = {
+       0xd1, /* MT29F1G08ABAFA */
+       0xa1, /* MT29F1G08ABBFA */
+};
+
 /*
  * 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
@@ -269,6 +277,11 @@ static int micron_supports_on_die_ecc(struct nand_chip 
*chip)
 {
        u8 feature[ONFI_SUBFEATURE_PARAM_LEN] = { 0, };
        int ret;
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(micron_on_die_ecc); i++)
+               if (chip->id.data[1] == micron_on_die_ecc[i])
+                       return MICRON_ON_DIE_MANDATORY;
 
        if (!chip->parameters.onfi.version)
                return MICRON_ON_DIE_UNSUPPORTED;
@@ -322,7 +335,8 @@ static int micron_nand_init(struct nand_chip *chip)
 
        ondie = micron_supports_on_die_ecc(chip);
 
-       if (ondie == MICRON_ON_DIE_MANDATORY) {
+       if (ondie == MICRON_ON_DIE_MANDATORY &&
+           chip->ecc.mode != NAND_ECC_ON_DIE) {
                pr_err("On-die ECC forcefully enabled, not supported\n");
                return -EINVAL;
        }
-- 
2.18.0