[PATCH 6.19 715/844] mtd: spinand: Disable continuous read during probe

[Sasha Levin]

From: David LaPorte <dalaport@xxxxxxxxxx>

[ Upstream commit b4af7d194dc879353829f3c56988a68fbba1fbdd ]

Macronix serial NAND devices with continuous read support do not
clear the configuration register on soft reset and lack a hardware
reset pin. When continuous read is interrupted (e.g., during reboot),
the feature remains enabled at the device level.

With continuous read enabled, the OOB area becomes inaccessible and
all reads are instead directed to the main area. As a result, during
partition allocation as part of MTD device registration, the first two
bytes of the main area for the master block are read and indicate that
the block is bad. This process repeats for every subsequent block for
the partition.

All reads and writes that reference the BBT find no good blocks and
fail.

The only paths for recovery from this state are triggering the
continuous read feature by way of raw MTD reads or through a NAND
device power drain.

Disable continuous read explicitly during spinand probe to ensure
quiescent feature state.

Fixes: 631cfdd0520d ("mtd: spi-nand: Add continuous read support")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: David LaPorte <dalaport@xxxxxxxxxx>
Reviewed-by: Gunnar Kudrjavets <gunnarku@xxxxxxxxxx>
Reviewed-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@xxxxxxxxx>
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/mtd/nand/spi/core.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index d207286572d87..9540fd04156c7 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -859,6 +859,14 @@ static void spinand_cont_read_init(struct spinand_device *spinand)
 	    (engine_type == NAND_ECC_ENGINE_TYPE_ON_DIE ||
 	     engine_type == NAND_ECC_ENGINE_TYPE_NONE)) {
 		spinand->cont_read_possible = true;
+
+		/*
+		 * Ensure continuous read is disabled on probe.
+		 * Some devices retain this state across soft reset,
+		 * which leaves the OOB area inaccessible and results
+		 * in false positive returns from spinand_isbad().
+		 */
+		spinand_cont_read_enable(spinand, false);
 	}
 }
 
-- 
2.51.0