generic: fix Macronix SPI-NAND driver

Use scratch buffer for DMA operetations. Passing a pointer to a stack
variable won't work and results in bogus bit flips being reported.

Patch was submitted upstream and is part of Linux 6.3.

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

diff --git a/target/linux/generic/backport-5.15/423-v6.3-mtd-spinand-macronix-use-scratch-buffer-for-DMA-oper.patch b/target/linux/generic/backport-5.15/423-v6.3-mtd-spinand-macronix-use-scratch-buffer-for-DMA-oper.patch
new file mode 100644 (file)
index 0000000..7dbc271
--- /dev/null
+++ b/target/linux/generic/backport-5.15/423-v6.3-mtd-spinand-macronix-use-scratch-buffer-for-DMA-oper.patch
@@ -0,0 +1,35 @@
+From ebed787a0becb9354f0a23620a5130cccd6c730c Mon Sep 17 00:00:00 2001
+From: Daniel Golle <daniel@makrotopia.org>
+Date: Thu, 19 Jan 2023 03:45:43 +0000
+Subject: [PATCH] mtd: spinand: macronix: use scratch buffer for DMA operation
+
+The mx35lf1ge4ab_get_eccsr() function uses an SPI DMA operation to
+read the eccsr, hence the buffer should not be on stack. Since commit
+380583227c0c7f ("spi: spi-mem: Add extra sanity checks on the op param")
+the kernel emmits a warning and blocks such operations.
+
+Use the scratch buffer to get eccsr instead of trying to directly read
+into a stack-allocated variable.
+
+Signed-off-by: Daniel Golle <daniel@makrotopia.org>
+Reviewed-by: Dhruva Gole <d-gole@ti.com>
+Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
+Link: https://lore.kernel.org/linux-mtd/Y8i85zM0u4XdM46z@makrotopia.org
+---
+ drivers/mtd/nand/spi/macronix.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+--- a/drivers/mtd/nand/spi/macronix.c
++++ b/drivers/mtd/nand/spi/macronix.c
+@@ -83,9 +83,10 @@ static int mx35lf1ge4ab_ecc_get_status(s
+                * in order to avoid forcing the wear-leveling layer to move
+                * data around if it's not necessary.
+                */
+-              if (mx35lf1ge4ab_get_eccsr(spinand, &eccsr))
++              if (mx35lf1ge4ab_get_eccsr(spinand, spinand->scratchbuf))
+                       return nanddev_get_ecc_conf(nand)->strength;
+ 
++              eccsr = *spinand->scratchbuf;
+               if (WARN_ON(eccsr > nanddev_get_ecc_conf(nand)->strength ||
+                           !eccsr))
+                       return nanddev_get_ecc_conf(nand)->strength;