[PATCH RESEND v2 0/4] mtd: spinand: fix continuous reading mode support

[PATCH RESEND v2 0/4] mtd: spinand: fix continuous reading mode support

[Mikhail Kshevetskiy]

Continuous reading mode is broken for some spi controllers. This may lead
to errors during reading of more than one flash page at once. This patch
series improve continuous mode support and add a fallback to regular
reading method if continuous reading is not supported by spi controller.

Changes v2:
 * added helper to create reading dirmap descriptor
 * fix spelling
 * error code is not used for regular reading fallback anymore
 * it's possible (but very unlucky) that someone will do raw reading
   of the flash in continuous mode (i.e. without OOB), so fix dirmap
   creation for that case as well.

Mikhail Kshevetskiy (4):
  mtd: spinand: fix direct mapping creation sizes.
  mtd: spinand: try a regular dirmap if creating a dirmap for continuous
    reading fails
  mtd: spinand: repeat reading in regular mode if continuous reading
    fails
  spi: spi-airoha-snfi: return an error for continuous mode dirmap
    creation cases

 drivers/mtd/nand/spi/core.c   | 88 +++++++++++++++++++++++++++--------
 drivers/spi/spi-airoha-snfi.c |  4 ++
 2 files changed, 72 insertions(+), 20 deletions(-)

-- 
2.50.1

[PATCH RESEND v2 1/4] mtd: spinand: fix direct mapping creation sizes.

[Mikhail Kshevetskiy]

Continuous mode is only supported for data reads, thus writing
requires only single flash page mapping.

Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
---
 drivers/mtd/nand/spi/core.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index b0898990b2a5..09dd6e40e308 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -1097,18 +1097,13 @@ static int spinand_create_dirmap(struct spinand_device *spinand,
 				 unsigned int plane)
 {
 	struct nand_device *nand = spinand_to_nand(spinand);
-	struct spi_mem_dirmap_info info = {
-		.length = nanddev_page_size(nand) +
-			  nanddev_per_page_oobsize(nand),
-	};
+	struct spi_mem_dirmap_info info = { 0 };
 	struct spi_mem_dirmap_desc *desc;
 
-	if (spinand->cont_read_possible)
-		info.length = nanddev_eraseblock_size(nand);
-
 	/* The plane number is passed in MSB just above the column address */
 	info.offset = plane << fls(nand->memorg.pagesize);
 
+	info.length = nanddev_page_size(nand) + nanddev_per_page_oobsize(nand);
 	info.op_tmpl = *spinand->op_templates.update_cache;
 	desc = devm_spi_mem_dirmap_create(&spinand->spimem->spi->dev,
 					  spinand->spimem, &info);
@@ -1117,6 +1112,8 @@ static int spinand_create_dirmap(struct spinand_device *spinand,
 
 	spinand->dirmaps[plane].wdesc = desc;
 
+	if (spinand->cont_read_possible)
+		info.length = nanddev_eraseblock_size(nand);
 	info.op_tmpl = *spinand->op_templates.read_cache;
 	desc = devm_spi_mem_dirmap_create(&spinand->spimem->spi->dev,
 					  spinand->spimem, &info);
@@ -1132,6 +1129,7 @@ static int spinand_create_dirmap(struct spinand_device *spinand,
 		return 0;
 	}
 
+	info.length = nanddev_page_size(nand) + nanddev_per_page_oobsize(nand);
 	info.op_tmpl = *spinand->op_templates.update_cache;
 	info.op_tmpl.data.ecc = true;
 	desc = devm_spi_mem_dirmap_create(&spinand->spimem->spi->dev,
@@ -1141,6 +1139,8 @@ static int spinand_create_dirmap(struct spinand_device *spinand,
 
 	spinand->dirmaps[plane].wdesc_ecc = desc;
 
+	if (spinand->cont_read_possible)
+		info.length = nanddev_eraseblock_size(nand);
 	info.op_tmpl = *spinand->op_templates.read_cache;
 	info.op_tmpl.data.ecc = true;
 	desc = devm_spi_mem_dirmap_create(&spinand->spimem->spi->dev,
-- 
2.50.1

[PATCH RESEND v2 2/4] mtd: spinand: try a regular dirmap if creating a dirmap for continuous reading fails

[Mikhail Kshevetskiy]

Continuous reading may result in multiple flash pages reading in one
operation. Typically only one flash page has read/written (a little bit
more than 2-4 Kb), but continuous reading requires the spi controller
to read up to 512 Kb in one operation without toggling CS in beetween.

Roughly speaking spi controllers can be divided on 2 categories:
 * spi controllers without dirmap acceleration support
 * spi controllers with dirmap acceleration support

Usually, first of them have no issues with large reading support.
Second group often supports acceleration of single page only reading.
Thus enabling of continuous reading can break flash reading.

This patch tries to create dirmap for continuous reading first and
fallback to regular reading if spi controller refuses to create it.

Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
---
 drivers/mtd/nand/spi/core.c | 43 ++++++++++++++++++++++++++++++-------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 09dd6e40e308..0f8636047365 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -1093,6 +1093,39 @@ static int spinand_mtd_block_isreserved(struct mtd_info *mtd, loff_t offs)
 	return ret;
 }
 
+static struct spi_mem_dirmap_desc *spinand_create_rdesc_helper(
+					struct spinand_device *spinand,
+					struct spi_mem_dirmap_info *info)
+{
+	struct nand_device *nand = spinand_to_nand(spinand);
+	struct spi_mem_dirmap_desc *desc = NULL;
+
+	if (spinand->cont_read_possible) {
+		/*
+		 * spi controller may return an error if info->length is
+		 * too large
+		 */
+		info->length = nanddev_eraseblock_size(nand);
+		desc = devm_spi_mem_dirmap_create(&spinand->spimem->spi->dev,
+						  spinand->spimem, info);
+	}
+
+	if (IS_ERR_OR_NULL(desc)) {
+		/*
+		 * continuous reading is not supported by flash or
+		 * its spi controller, use regular reading
+		 */
+		spinand->cont_read_possible = false;
+
+		info->length = nanddev_page_size(nand) +
+			       nanddev_per_page_oobsize(nand);
+		desc = devm_spi_mem_dirmap_create(&spinand->spimem->spi->dev,
+						  spinand->spimem, info);
+	}
+
+	return desc;
+}
+
 static int spinand_create_dirmap(struct spinand_device *spinand,
 				 unsigned int plane)
 {
@@ -1112,11 +1145,8 @@ static int spinand_create_dirmap(struct spinand_device *spinand,
 
 	spinand->dirmaps[plane].wdesc = desc;
 
-	if (spinand->cont_read_possible)
-		info.length = nanddev_eraseblock_size(nand);
 	info.op_tmpl = *spinand->op_templates.read_cache;
-	desc = devm_spi_mem_dirmap_create(&spinand->spimem->spi->dev,
-					  spinand->spimem, &info);
+	desc = spinand_create_rdesc_helper(spinand, &info);
 	if (IS_ERR(desc))
 		return PTR_ERR(desc);
 
@@ -1139,12 +1169,9 @@ static int spinand_create_dirmap(struct spinand_device *spinand,
 
 	spinand->dirmaps[plane].wdesc_ecc = desc;
 
-	if (spinand->cont_read_possible)
-		info.length = nanddev_eraseblock_size(nand);
 	info.op_tmpl = *spinand->op_templates.read_cache;
 	info.op_tmpl.data.ecc = true;
-	desc = devm_spi_mem_dirmap_create(&spinand->spimem->spi->dev,
-					  spinand->spimem, &info);
+	desc = spinand_create_rdesc_helper(spinand, &info);
 	if (IS_ERR(desc))
 		return PTR_ERR(desc);
 
-- 
2.50.1

[PATCH RESEND v2 3/4] mtd: spinand: repeat reading in regular mode if continuous reading fails

[Mikhail Kshevetskiy]

Continuous reading may result in multiple flash pages reading in one
operation. Unfortunately, not all spinand controllers support such
large reading. They will read less data. Unfortunately, the operation
can't be continued.

In this case:
 * disable continuous reading on this (not good enough) spi controller
 * repeat reading in regular mode.

Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
---
 drivers/mtd/nand/spi/core.c | 39 ++++++++++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 9 deletions(-)

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 0f8636047365..5528e1f72dbc 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -378,7 +378,8 @@ static int spinand_load_page_op(struct spinand_device *spinand,
 }
 
 static int spinand_read_from_cache_op(struct spinand_device *spinand,
-				      const struct nand_page_io_req *req)
+				      const struct nand_page_io_req *req,
+				      bool *controller_is_buggy)
 {
 	struct nand_device *nand = spinand_to_nand(spinand);
 	struct mtd_info *mtd = spinand_to_mtd(spinand);
@@ -430,8 +431,11 @@ static int spinand_read_from_cache_op(struct spinand_device *spinand,
 		 * Dirmap accesses are allowed to toggle the CS.
 		 * Toggling the CS during a continuous read is forbidden.
 		 */
-		if (nbytes && req->continuous)
+		if (nbytes && req->continuous) {
+			if (controller_is_buggy)
+				*controller_is_buggy = true;
 			return -EIO;
+		}
 	}
 
 	if (req->datalen)
@@ -646,7 +650,7 @@ int spinand_read_page(struct spinand_device *spinand,
 
 	spinand_ondie_ecc_save_status(nand, status);
 
-	ret = spinand_read_from_cache_op(spinand, req);
+	ret = spinand_read_from_cache_op(spinand, req, NULL);
 	if (ret)
 		return ret;
 
@@ -770,7 +774,8 @@ static int spinand_mtd_regular_page_read(struct mtd_info *mtd, loff_t from,
 
 static int spinand_mtd_continuous_page_read(struct mtd_info *mtd, loff_t from,
 					    struct mtd_oob_ops *ops,
-					    unsigned int *max_bitflips)
+					    unsigned int *max_bitflips,
+					    bool *controller_is_buggy)
 {
 	struct spinand_device *spinand = mtd_to_spinand(mtd);
 	struct nand_device *nand = mtd_to_nanddev(mtd);
@@ -808,7 +813,7 @@ static int spinand_mtd_continuous_page_read(struct mtd_info *mtd, loff_t from,
 		if (ret < 0)
 			goto end_cont_read;
 
-		ret = spinand_read_from_cache_op(spinand, &iter.req);
+		ret = spinand_read_from_cache_op(spinand, &iter.req, controller_is_buggy);
 		if (ret)
 			goto end_cont_read;
 
@@ -892,6 +897,7 @@ static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,
 {
 	struct spinand_device *spinand = mtd_to_spinand(mtd);
 	struct mtd_ecc_stats old_stats;
+	bool controller_is_buggy = false;
 	unsigned int max_bitflips = 0;
 	int ret;
 
@@ -899,10 +905,25 @@ static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,
 
 	old_stats = mtd->ecc_stats;
 
-	if (spinand_use_cont_read(mtd, from, ops))
-		ret = spinand_mtd_continuous_page_read(mtd, from, ops, &max_bitflips);
-	else
-		ret = spinand_mtd_regular_page_read(mtd, from, ops, &max_bitflips);
+	if (spinand_use_cont_read(mtd, from, ops)) {
+		ret = spinand_mtd_continuous_page_read(mtd, from, ops,
+						       &max_bitflips,
+						       &controller_is_buggy);
+		if (controller_is_buggy) {
+			/*
+			 * Some spi controllers may not support reading up to
+			 * erase block size. They will read less data than
+			 * expected. If this happen disable continuous mode
+			 * and repeat reading in normal mode.
+			 */
+			spinand->cont_read_possible = false;
+			ret = spinand_mtd_regular_page_read(mtd, from, ops,
+							    &max_bitflips);
+		}
+	} else {
+		ret = spinand_mtd_regular_page_read(mtd, from, ops,
+						    &max_bitflips);
+	}
 
 	if (ops->stats) {
 		ops->stats->uncorrectable_errors +=
-- 
2.50.1

[PATCH RESEND v2 4/4] spi: spi-airoha-snfi: return an error for continuous mode dirmap creation cases

[Mikhail Kshevetskiy]

This driver can accelerate single page operations only, thus
continuous reading mode should not be used.

Continuous reading will use sizes up to the size of one erase block.
This size is much larger than the size of single flash page. Use this
difference to identify continuous reading and return an error.

Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
---
 drivers/spi/spi-airoha-snfi.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/spi/spi-airoha-snfi.c b/drivers/spi/spi-airoha-snfi.c
index dbe640986825..043a03cd90a1 100644
--- a/drivers/spi/spi-airoha-snfi.c
+++ b/drivers/spi/spi-airoha-snfi.c
@@ -618,6 +618,10 @@ static int airoha_snand_dirmap_create(struct spi_mem_dirmap_desc *desc)
 	if (desc->info.offset + desc->info.length > U32_MAX)
 		return -EINVAL;
 
+	/* continuous reading is not supported */
+	if (desc->info.length > SPI_NAND_CACHE_SIZE)
+		return -E2BIG;
+
 	if (!airoha_snand_supports_op(desc->mem, &desc->info.op_tmpl))
 		return -EOPNOTSUPP;
 
-- 
2.50.1

Re: [PATCH RESEND v2 4/4] spi: spi-airoha-snfi: return an error for continuous mode dirmap creation cases

[Mark Brown]

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On Thu, Aug 14, 2025 at 09:54:23AM +0300, Mikhail Kshevetskiy wrote:
> This driver can accelerate single page operations only, thus
> continuous reading mode should not be used.
> 
> Continuous reading will use sizes up to the size of one erase block.
> This size is much larger than the size of single flash page. Use this
> difference to identify continuous reading and return an error.

This seems like it just applies anyway regardless of the rest of the
series?

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Re: [PATCH RESEND v2 4/4] spi: spi-airoha-snfi: return an error for continuous mode dirmap creation cases

[Mikhail Kshevetskiy]

On 14.08.2025 18:29, Mark Brown wrote:
> On Thu, Aug 14, 2025 at 09:54:23AM +0300, Mikhail Kshevetskiy wrote:
>> This driver can accelerate single page operations only, thus
>> continuous reading mode should not be used.
>>
>> Continuous reading will use sizes up to the size of one erase block.
>> This size is much larger than the size of single flash page. Use this
>> difference to identify continuous reading and return an error.
> This seems like it just applies anyway regardless of the rest of the
> series?

Could you provide a link? I do not see this in upstream linux repo.

Mikhail Kshevetskiy

Re: [PATCH RESEND v2 4/4] spi: spi-airoha-snfi: return an error for continuous mode dirmap creation cases

[Frieder Schrempf]

Am 14.08.25 um 08:54 schrieb Mikhail Kshevetskiy:
> This driver can accelerate single page operations only, thus
> continuous reading mode should not be used.
> 
> Continuous reading will use sizes up to the size of one erase block.
> This size is much larger than the size of single flash page. Use this
> difference to identify continuous reading and return an error.
> 
> Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>

Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>

Re: [PATCH RESEND v2 4/4] spi: spi-airoha-snfi: return an error for continuous mode dirmap creation cases

[Frieder Schrempf]

Am 14.08.25 um 17:33 schrieb Mikhail Kshevetskiy:
> 
> On 14.08.2025 18:29, Mark Brown wrote:
>> On Thu, Aug 14, 2025 at 09:54:23AM +0300, Mikhail Kshevetskiy wrote:
>>> This driver can accelerate single page operations only, thus
>>> continuous reading mode should not be used.
>>>
>>> Continuous reading will use sizes up to the size of one erase block.
>>> This size is much larger than the size of single flash page. Use this
>>> difference to identify continuous reading and return an error.
>> This seems like it just applies anyway regardless of the rest of the
>> series?
> 
> Could you provide a link? I do not see this in upstream linux repo.

Mark asked if this could be applied without the other patches of this
series through his SPI tree and I think that is indeed correct. The
other patches are still being reviewed and applied via the MTD tree.

Re: [PATCH RESEND v2 4/4] spi: spi-airoha-snfi: return an error for continuous mode dirmap creation cases

[Mikhail Kshevetskiy]

On 20.08.2025 11:49, Frieder Schrempf wrote:
> Am 14.08.25 um 17:33 schrieb Mikhail Kshevetskiy:
>> On 14.08.2025 18:29, Mark Brown wrote:
>>> On Thu, Aug 14, 2025 at 09:54:23AM +0300, Mikhail Kshevetskiy wrote:
>>>> This driver can accelerate single page operations only, thus
>>>> continuous reading mode should not be used.
>>>>
>>>> Continuous reading will use sizes up to the size of one erase block.
>>>> This size is much larger than the size of single flash page. Use this
>>>> difference to identify continuous reading and return an error.
>>> This seems like it just applies anyway regardless of the rest of the
>>> series?
>> Could you provide a link? I do not see this in upstream linux repo.
> Mark asked if this could be applied without the other patches of this
> series through his SPI tree and I think that is indeed correct. The
> other patches are still being reviewed and applied via the MTD tree.
Thanks for clarification. I could add it to other aihoha spi driver fixes.

Mikhail

Re: [PATCH RESEND v2 4/4] spi: spi-airoha-snfi: return an error for continuous mode dirmap creation cases

[Lorenzo Bianconi]

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> Am 14.08.25 um 17:33 schrieb Mikhail Kshevetskiy:
> > 
> > On 14.08.2025 18:29, Mark Brown wrote:
> >> On Thu, Aug 14, 2025 at 09:54:23AM +0300, Mikhail Kshevetskiy wrote:
> >>> This driver can accelerate single page operations only, thus
> >>> continuous reading mode should not be used.
> >>>
> >>> Continuous reading will use sizes up to the size of one erase block.
> >>> This size is much larger than the size of single flash page. Use this
> >>> difference to identify continuous reading and return an error.
> >> This seems like it just applies anyway regardless of the rest of the
> >> series?
> > 
> > Could you provide a link? I do not see this in upstream linux repo.
> 
> Mark asked if this could be applied without the other patches of this
> series through his SPI tree and I think that is indeed correct. The
> other patches are still being reviewed and applied via the MTD tree.

Can you please add the following Fixes tag?

Fixes: a403997c12019 ("spi: airoha: add SPI-NAND Flash controller driver")

Regards,
Lorenzo

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Re: [PATCH RESEND v2 4/4] spi: spi-airoha-snfi: return an error for continuous mode dirmap creation cases

[Miquel Raynal]

On 14/08/2025 at 18:33:25 +03, Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu> wrote:

> On 14.08.2025 18:29, Mark Brown wrote:
>> On Thu, Aug 14, 2025 at 09:54:23AM +0300, Mikhail Kshevetskiy wrote:
>>> This driver can accelerate single page operations only, thus
>>> continuous reading mode should not be used.
>>>
>>> Continuous reading will use sizes up to the size of one erase block.
>>> This size is much larger than the size of single flash page. Use this
>>> difference to identify continuous reading and return an error.
>> This seems like it just applies anyway regardless of the rest of the
>> series?
>
> Could you provide a link? I do not see this in upstream linux repo.

No link, Mark can apply this without the rest of the series it seems. If
that's the case, it's best to send two series because these patches
apply to different trees.

Thanks,
Miquèl

Re: [PATCH RESEND v2 3/4] mtd: spinand: repeat reading in regular mode if continuous reading fails

[Miquel Raynal]

Hello,

> +		if (controller_is_buggy) {
> +			/*
> +			 * Some spi controllers may not support reading up to
> +			 * erase block size. They will read less data than
> +			 * expected. If this happen disable continuous mode
> +			 * and repeat reading in normal mode.
> +			 */
> +			spinand->cont_read_possible = false;

I am fine with the idea, but could we avoid this little dance and drop
the extra controller_is_buggy boolean, and just let
spinand_mtd_continuous_page_read() do the fixup and return -EAGAIN?

> +			ret = spinand_mtd_regular_page_read(mtd, from, ops,
> +							    &max_bitflips);
> +		}
> +	} else {
> +		ret = spinand_mtd_regular_page_read(mtd, from, ops,
> +						    &max_bitflips);
> +	}
>  
>  	if (ops->stats) {
>  		ops->stats->uncorrectable_errors +=

Thanks,
Miquèl

Re: [PATCH RESEND v2 2/4] mtd: spinand: try a regular dirmap if creating a dirmap for continuous reading fails

[Miquel Raynal]

On 14/08/2025 at 09:54:21 +03, Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu> wrote:

> Continuous reading may result in multiple flash pages reading in one
> operation. Typically only one flash page has read/written (a little bit
> more than 2-4 Kb), but continuous reading requires the spi controller
> to read up to 512 Kb in one operation without toggling CS in beetween.
>
> Roughly speaking spi controllers can be divided on 2 categories:
>  * spi controllers without dirmap acceleration support
>  * spi controllers with dirmap acceleration support
>
> Usually, first of them have no issues with large reading support.
> Second group often supports acceleration of single page only reading.
> Thus enabling of continuous reading can break flash reading.
>
> This patch tries to create dirmap for continuous reading first and
> fallback to regular reading if spi controller refuses to create it.
>
> Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
> ---
>  drivers/mtd/nand/spi/core.c | 43 ++++++++++++++++++++++++++++++-------
>  1 file changed, 35 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> index 09dd6e40e308..0f8636047365 100644
> --- a/drivers/mtd/nand/spi/core.c
> +++ b/drivers/mtd/nand/spi/core.c
> @@ -1093,6 +1093,39 @@ static int spinand_mtd_block_isreserved(struct mtd_info *mtd, loff_t offs)
>  	return ret;
>  }
>  
> +static struct spi_mem_dirmap_desc *spinand_create_rdesc_helper(

Can we drop _helper from the name? Just spinand_create_rdesc() sounds
as useful.

> +					struct spinand_device *spinand,
> +					struct spi_mem_dirmap_info *info)
> +{
> +	struct nand_device *nand = spinand_to_nand(spinand);
> +	struct spi_mem_dirmap_desc *desc = NULL;
> +

Looks good otherwise.

Thanks,
Miquèl