This is a note to let you know that I've just added the patch titled
mtd: rawnand: arasan: Prevent an unsupported configuration
to the 5.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mtd-rawnand-arasan-prevent-an-unsupported-configurat.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7cda4797ced572e4d1204dc7c7eda77508b0ce78
Author: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Date: Fri Oct 8 18:36:40 2021 +0200
mtd: rawnand: arasan: Prevent an unsupported configuration
[ Upstream commit fc9e18f9e987ad46722dad53adab1c12148c213c ]
Under the following conditions:
* after rounding up by 4 the number of bytes to transfer (this is
related to the controller's internal constraints),
* if this (rounded) amount of data is situated beyond the end of the
device,
* and only in NV-DDR mode,
the Arasan NAND controller timeouts.
This currently can happen in a particular helper used when picking
software ECC algorithms. Let's prevent this situation by refusing to use
the NV-DDR interface with software engines.
Fixes: 4edde6031458 ("mtd: rawnand: arasan: Support NV-DDR interface")
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Link: https://lore.kernel.org/linux-mtd/20211008163640.1753821-1-miquel.raynal@xxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/mtd/nand/raw/arasan-nand-controller.c b/drivers/mtd/nand/raw/arasan-nand-controller.c
index 9cbcc698c64d8..53bd10738418b 100644
--- a/drivers/mtd/nand/raw/arasan-nand-controller.c
+++ b/drivers/mtd/nand/raw/arasan-nand-controller.c
@@ -973,6 +973,21 @@ static int anfc_setup_interface(struct nand_chip *chip, int target,
nvddr = nand_get_nvddr_timings(conf);
if (IS_ERR(nvddr))
return PTR_ERR(nvddr);
+
+ /*
+ * The controller only supports data payload requests which are
+ * a multiple of 4. In practice, most data accesses are 4-byte
+ * aligned and this is not an issue. However, rounding up will
+ * simply be refused by the controller if we reached the end of
+ * the device *and* we are using the NV-DDR interface(!). In
+ * this situation, unaligned data requests ending at the device
+ * boundary will confuse the controller and cannot be performed.
+ *
+ * This is something that happens in nand_read_subpage() when
+ * selecting software ECC support and must be avoided.
+ */
+ if (chip->ecc.engine_type == NAND_ECC_ENGINE_TYPE_SOFT)
+ return -ENOTSUPP;
} else {
sdr = nand_get_sdr_timings(conf);
if (IS_ERR(sdr))
