* [PATCH v2] mtd: rawnand: arasan: Prevent an unsupported configuration
@ 2021-10-08 16:36 Miquel Raynal
2021-10-15 10:31 ` Miquel Raynal
0 siblings, 1 reply; 2+ messages in thread
From: Miquel Raynal @ 2021-10-08 16:36 UTC (permalink / raw)
To: Naga Sureshkumar Relli, Michal Simek, Amit Kumar Mahapatra,
Richard Weinberger, Vignesh Raghavendra, Tudor Ambarus
Cc: linux-mtd, Thomas Petazzoni, Boris Brezillon, Miquel Raynal
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@bootlin.com>
---
Changes in v2:
As v1 was too invasive Boris suggested to adopt a much simpler approach:
let's just avoid the situation. That's what I am doing here.
drivers/mtd/nand/raw/arasan-nand-controller.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/mtd/nand/raw/arasan-nand-controller.c b/drivers/mtd/nand/raw/arasan-nand-controller.c
index 9cbcc698c64d..53bd10738418 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))
--
2.27.0
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] mtd: rawnand: arasan: Prevent an unsupported configuration
2021-10-08 16:36 [PATCH v2] mtd: rawnand: arasan: Prevent an unsupported configuration Miquel Raynal
@ 2021-10-15 10:31 ` Miquel Raynal
0 siblings, 0 replies; 2+ messages in thread
From: Miquel Raynal @ 2021-10-15 10:31 UTC (permalink / raw)
To: Miquel Raynal, Naga Sureshkumar Relli, Michal Simek,
Amit Kumar Mahapatra, Richard Weinberger, Vignesh Raghavendra,
Tudor Ambarus
Cc: linux-mtd, Thomas Petazzoni, Boris Brezillon
On Fri, 2021-10-08 at 16:36:40 UTC, Miquel Raynal wrote:
> 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@bootlin.com>
Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git nand/next.
Miquel
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Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/
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