linux-kernel - [PATCH] spi: spi-qpic-snand: simplify bad block marker duplication

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Message-Id: <20250711-qpic-snand-simplify-bbm-copy-v1-1-dd2608325f72@gmail.com>
Date: Fri, 11 Jul 2025 18:32:52 +0200
From: Gabor Juhos <j4g8y7@...il.com>
To: Mark Brown <broonie@...nel.org>
Cc: Varadarajan Narayanan <quic_varada@...cinc.com>, 
 Md Sadre Alam <quic_mdalam@...cinc.com>, 
 Sricharan Ramabadhran <quic_srichara@...cinc.com>, 
 linux-spi@...r.kernel.org, linux-mtd@...ts.infradead.org, 
 linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Gabor Juhos <j4g8y7@...il.com>
Subject: [PATCH] spi: spi-qpic-snand: simplify bad block marker duplication

Due to the expectations of the SPINAND code, the driver duplicates
the bad block markers during raw OOB reads.

It has been implemented by using two if statements, and due to the
opposite conditions one of conditional codepaths always runs. Since
the effect of both codepaths is the same, remove the if statements
and use a single line solution instead.

Also add a note about why the duplication is required.

No functional changes intended.

Signed-off-by: Gabor Juhos <j4g8y7@...il.com>
---
 drivers/spi/spi-qpic-snand.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-qpic-snand.c b/drivers/spi/spi-qpic-snand.c
index b711c8be42c1f76029497b0c17d00cd8e52f5aa2..94c4d76cee34420d1dc3894aadad0086c6f22d96 100644
--- a/drivers/spi/spi-qpic-snand.c
+++ b/drivers/spi/spi-qpic-snand.c
@@ -597,10 +597,16 @@ static int qcom_spi_read_last_cw(struct qcom_nand_controller *snandc,
 
 	bbpos = mtd->writesize - ecc_cfg->cw_size * (num_cw - 1);
 
-	if (snandc->data_buffer[bbpos] == 0xff)
-		snandc->data_buffer[bbpos + 1] = 0xff;
-	if (snandc->data_buffer[bbpos] != 0xff)
-		snandc->data_buffer[bbpos + 1] = snandc->data_buffer[bbpos];
+	/*
+	 * TODO: The SPINAND code expects two bad block marker bytes
+	 * at the beginning of the OOB area, but the OOB layout used by
+	 * the driver has only one. Duplicate that for now in order to
+	 * avoid certain blocks to be marked as bad.
+	 *
+	 * This can be removed once single-byte bad block marker support
+	 * gets implemented in the SPINAND code.
+	 */
+	snandc->data_buffer[bbpos + 1] = snandc->data_buffer[bbpos];
 
 	memcpy(op->data.buf.in, snandc->data_buffer + bbpos, op->data.nbytes);
 

---
base-commit: 7d61715c58a39edc5f74fc7366487726fc223530
change-id: 20250710-qpic-snand-simplify-bbm-copy-82cc0e0022c7

Best regards,
-- 
Gabor Juhos <j4g8y7@...il.com>