generic: import patch lowering bitflip_threshold on SPI-NAND

Reporting an unclean read from SPI-NAND only when the maximum number
of correctable bitflip errors has been hit seems a bit late.
UBI LEB scrubbing, which depends on the lower MTD device reporting
correctable bitflips, then only kicks in when it's almost too late.

Set bitflip_threshold to 75% of the ECC strength, which is also the
default for raw NAND.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

2 files changed, 66 insertions, 3 deletions

diff --git a/target/linux/generic/pending-6.6/410-mtd-spinand-set-bitflip_threshold-to-75-of-ECC-strength.patch b/target/linux/generic/pending-6.6/410-mtd-spinand-set-bitflip_threshold-to-75-of-ECC-strength.patch
new file mode 100644
index 0000000000..aeac79c023
--- /dev/null
+++ b/target/linux/generic/pending-6.6/410-mtd-spinand-set-bitflip_threshold-to-75-of-ECC-strength.patch
@@ -0,0 +1,63 @@
+From patchwork Mon Aug 12 01:56:41 2024
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+X-Patchwork-Submitter: Daniel Golle <daniel@makrotopia.org>
+X-Patchwork-Id: 1971406
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+ <linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org>
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+Delivered-To: patchwork-incoming@legolas.ozlabs.org
+Date: Mon, 12 Aug 2024 02:56:41 +0100
+From: Daniel Golle <daniel@makrotopia.org>
+To: Miquel Raynal <miquel.raynal@bootlin.com>,
+	Richard Weinberger <richard@nod.at>,
+	Vignesh Raghavendra <vigneshr@ti.com>,
+	Tudor Ambarus <tudor.ambarus@linaro.org>,
+	Daniel Golle <daniel@makrotopia.org>,
+	Mika Westerberg <mika.westerberg@linux.intel.com>,
+	Chia-Lin Kao <acelan.kao@canonical.com>,
+	Martin Kurbanov <mmkurbanov@salutedevices.com>,
+	linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org
+Subject: [PATCH] mtd: spinand: set bitflip_threshold to 75% of ECC strength
+Message-ID: 
+ <2117e387260b0a96f95b8e1652ff79e0e2d71d53.1723427450.git.daniel@makrotopia.org>
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+
+Reporting an unclean read from SPI-NAND only when the maximum number
+of correctable bitflip errors has been hit seems a bit late.
+UBI LEB scrubbing, which depends on the lower MTD device reporting
+correctable bitflips, then only kicks in when it's almost too late.
+
+Set bitflip_threshold to 75% of the ECC strength, which is also the
+default for raw NAND.
+
+Signed-off-by: Daniel Golle <daniel@makrotopia.org>
+---
+ drivers/mtd/nand/spi/core.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+--- a/drivers/mtd/nand/spi/core.c
++++ b/drivers/mtd/nand/spi/core.c
+@@ -1286,6 +1286,7 @@ static int spinand_init(struct spinand_d
+ 	/* Propagate ECC information to mtd_info */
+ 	mtd->ecc_strength = nanddev_get_ecc_conf(nand)->strength;
+ 	mtd->ecc_step_size = nanddev_get_ecc_conf(nand)->step_size;
++	mtd->bitflip_threshold = DIV_ROUND_UP(mtd->ecc_strength * 3, 4);
+ 
+ 	ret = spinand_create_dirmaps(spinand);
+ 	if (ret) {
diff --git a/target/linux/mediatek/patches-6.6/330-snand-mtk-bmt-support.patch b/target/linux/mediatek/patches-6.6/330-snand-mtk-bmt-support.patch
index 8a4ec2bcbd..de8e880643 100644
--- a/target/linux/mediatek/patches-6.6/330-snand-mtk-bmt-support.patch
+++ b/target/linux/mediatek/patches-6.6/330-snand-mtk-bmt-support.patch
@@ -8,7 +8,7 @@
  
  static int spinand_read_reg_op(struct spinand_device *spinand, u8 reg, u8 *val)
  {
-@@ -1345,6 +1346,7 @@ static int spinand_probe(struct spi_mem
+@@ -1346,6 +1347,7 @@ static int spinand_probe(struct spi_mem
  	if (ret)
  		return ret;
  
@@ -16,7 +16,7 @@
  	ret = mtd_device_register(mtd, NULL, 0);
  	if (ret)
  		goto err_spinand_cleanup;
-@@ -1352,6 +1354,7 @@ static int spinand_probe(struct spi_mem
+@@ -1353,6 +1355,7 @@ static int spinand_probe(struct spi_mem
  	return 0;
  
  err_spinand_cleanup:
@@ -24,7 +24,7 @@
  	spinand_cleanup(spinand);
  
  	return ret;
-@@ -1370,6 +1373,7 @@ static int spinand_remove(struct spi_mem
+@@ -1371,6 +1374,7 @@ static int spinand_remove(struct spi_mem
  	if (ret)
  		return ret;