[PATCH v9 08/18] mtd: rawnand: sunxi: preserve synthesized zero-pattern data and OOB

[James Hilliard]

ECC exception mode recognizes physical all-zero and all-ones chunks.
sunxi_nfc_hw_ecc_correct() fills their data and requested OOB buffers with
the detected pattern, but sets its erased flag only for all-ones chunks.

The caller skips normal buffer retrieval only when that flag is set. For
an all-zero chunk, PIO therefore overwrites the synthesized zeros with
SRAM contents. With scrambling enabled, those contents are descrambled
data rather than the physical zero pattern, yet the read reports success.
Requested OOB is also reloaded after synthesis, in both PIO and DMA.

After checking for ECC errors, skip buffer retrieval for either detected
pattern. Keep the erased flag separate: only all-ones chunks may set the
page's has_erased_chunk state, which controls randomization when reading
the trailing OOB. Preserve that state if an earlier chunk was erased.
ECC-error steps still take the existing raw reread and erased-page check.

Fixes: cc6822fb756b ("mtd: nand: sunxi: move some ECC related operations to their own functions")
Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
Closes: https://lore.kernel.org/r/sashiko-outbox-172123@xxxxxxxxxx
Signed-off-by: James Hilliard <james.hilliard1@xxxxxxxxx>
---
 drivers/mtd/nand/raw/sunxi_nand.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c
index 22cc8998d49c..82af3ccad885 100644
--- a/drivers/mtd/nand/raw/sunxi_nand.c
+++ b/drivers/mtd/nand/raw/sunxi_nand.c
@@ -1231,8 +1231,9 @@ static int sunxi_nfc_oob_read_batch(struct nand_chip *nand,
 			continue;
 		}
 
-		if (erased) {
-			read->has_erased_chunk = true;
+		/* Both patterns are already filled; only all-ones is erased. */
+		if (pattern_found & BIT(i)) {
+			read->has_erased_chunk |= erased;
 			continue;
 		}
 

-- 
2.53.0