[openwrt/openwrt] generic: backport fix for Winbond SPI NAND

[LEDE Commits]

dangole pushed a commit to openwrt/openwrt.git, branch openwrt-23.05:
https://git.openwrt.org/b59d02becc8714fa629cbccb3933db15d9ee110b

commit b59d02becc8714fa629cbccb3933db15d9ee110b
Author: Daniel Golle <daniel at makrotopia.org>
AuthorDate: Sun Aug 13 14:52:44 2023 +0100

    generic: backport fix for Winbond SPI NAND
    
    Avoid using stack allocated memory for DMA operations.
    
    Fixes: 156c00dedc ("generic: backport Winbond W25N02KV SPI-NAND support")
    Signed-off-by: Daniel Golle <daniel at makrotopia.org>
    (cherry picked from commit e6f8b699189139f09c3685332310ff870610de5e)
---
 ....5-mtd-spinand-winbond-Fix-ecc_get_status.patch | 49 ++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/target/linux/generic/backport-5.15/892-v6.5-mtd-spinand-winbond-Fix-ecc_get_status.patch b/target/linux/generic/backport-5.15/892-v6.5-mtd-spinand-winbond-Fix-ecc_get_status.patch
new file mode 100644
index 0000000000..2f408f5a30
--- /dev/null
+++ b/target/linux/generic/backport-5.15/892-v6.5-mtd-spinand-winbond-Fix-ecc_get_status.patch
@@ -0,0 +1,49 @@
+From f5a05060670a4d8d6523afc7963eb559c2e3615f Mon Sep 17 00:00:00 2001
+From: Olivier Maignial <olivier.maignial at hotmail.fr>
+Date: Fri, 23 Jun 2023 17:33:37 +0200
+Subject: [PATCH] mtd: spinand: winbond: Fix ecc_get_status
+
+Reading ECC status is failing.
+
+w25n02kv_ecc_get_status() is using on-stack buffer for
+SPINAND_GET_FEATURE_OP() output. It is not suitable for
+DMA needs of spi-mem.
+
+Fix this by using the spi-mem operations dedicated buffer
+spinand->scratchbuf.
+
+See
+spinand->scratchbuf:
+https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/mtd/spinand.h?h=v6.3#n418
+spi_mem_check_op():
+https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/spi/spi-mem.c?h=v6.3#n199
+
+Fixes: 6154c7a58348 ("mtd: spinand: winbond: add Winbond W25N02KV flash support")
+Cc: stable at vger.kernel.org
+Signed-off-by: Olivier Maignial <olivier.maignial at hotmail.fr>
+Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
+Link: https://lore.kernel.org/linux-mtd/DB4P250MB1032EDB9E36B764A33769039FE23A@DB4P250MB1032.EURP250.PROD.OUTLOOK.COM
+---
+ drivers/mtd/nand/spi/winbond.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/drivers/mtd/nand/spi/winbond.c
++++ b/drivers/mtd/nand/spi/winbond.c
+@@ -108,7 +108,7 @@ static int w25n02kv_ecc_get_status(struc
+ {
+ 	struct nand_device *nand = spinand_to_nand(spinand);
+ 	u8 mbf = 0;
+-	struct spi_mem_op op = SPINAND_GET_FEATURE_OP(0x30, &mbf);
++	struct spi_mem_op op = SPINAND_GET_FEATURE_OP(0x30, spinand->scratchbuf);
+ 
+ 	switch (status & STATUS_ECC_MASK) {
+ 	case STATUS_ECC_NO_BITFLIPS:
+@@ -126,7 +126,7 @@ static int w25n02kv_ecc_get_status(struc
+ 		if (spi_mem_exec_op(spinand->spimem, &op))
+ 			return nanddev_get_ecc_conf(nand)->strength;
+ 
+-		mbf >>= 4;
++		mbf = *(spinand->scratchbuf) >> 4;
+ 
+ 		if (WARN_ON(mbf > nanddev_get_ecc_conf(nand)->strength || !mbf))
+ 			return nanddev_get_ecc_conf(nand)->strength;