[PATCH] mtd: rawnand: fsmc: Default to autodetect buswidth

[PATCH] mtd: rawnand: fsmc: Default to autodetect buswidth

[Linus Walleij]

If you don't specify buswidth 2 (16 bits) in the device
tree, FSMC doesn't even probe anymore:

fsmc-nand 10100000.flash: FSMC device partno 090,
  manufacturer 80, revision 00, config 00
nand: device found, Manufacturer ID: 0x20, Chip ID: 0xb1
nand: ST Micro 10100000.flash
nand: bus width 8 instead of 16 bits
nand: No NAND device found
fsmc-nand 10100000.flash: probe with driver fsmc-nand failed
  with error -22

With this patch to use autodetection unless buswidth is
specified, the device is properly detected again:

fsmc-nand 10100000.flash: FSMC device partno 090,
  manufacturer 80, revision 00, config 00
nand: device found, Manufacturer ID: 0x20, Chip ID: 0xb1
nand: ST Micro NAND 128MiB 1,8V 16-bit
nand: 128 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB size: 64
fsmc-nand 10100000.flash: Using 1-bit HW ECC scheme
Scanning device for bad blocks

I don't know where or how this happened, I think some change
in the nand core.

Cc: stable@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/mtd/nand/raw/fsmc_nand.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/fsmc_nand.c b/drivers/mtd/nand/raw/fsmc_nand.c
index df61db8ce466593d533e617c141a8d2498b3a180..154fd9bea3016b2fa7fa720a41ef9eeed6063fd5 100644
--- a/drivers/mtd/nand/raw/fsmc_nand.c
+++ b/drivers/mtd/nand/raw/fsmc_nand.c
@@ -879,7 +879,9 @@ static int fsmc_nand_probe_config_dt(struct platform_device *pdev,
 		} else if (val != 1) {
 			dev_err(&pdev->dev, "invalid bank-width %u\n", val);
 			return -EINVAL;
-		}
+		};
+	} else {
+		nand->options |= NAND_BUSWIDTH_AUTO;
 	}
 
 	if (of_property_read_bool(np, "nand-skip-bbtscan"))

---
base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
change-id: 20250914-fsmc-bd18e1a8116f

Best regards,
-- 
Linus Walleij <linus.walleij@linaro.org>

Re: [PATCH] mtd: rawnand: fsmc: Default to autodetect buswidth

[Miquel Raynal]

Hi Linus,

On 14/09/2025 at 00:35:37 +02, Linus Walleij <linus.walleij@linaro.org> wrote:

> If you don't specify buswidth 2 (16 bits) in the device
> tree, FSMC doesn't even probe anymore:
>
> fsmc-nand 10100000.flash: FSMC device partno 090,
>   manufacturer 80, revision 00, config 00
> nand: device found, Manufacturer ID: 0x20, Chip ID: 0xb1
> nand: ST Micro 10100000.flash
> nand: bus width 8 instead of 16 bits
> nand: No NAND device found
> fsmc-nand 10100000.flash: probe with driver fsmc-nand failed
>   with error -22
>
> With this patch to use autodetection unless buswidth is
> specified, the device is properly detected again:
>
> fsmc-nand 10100000.flash: FSMC device partno 090,
>   manufacturer 80, revision 00, config 00
> nand: device found, Manufacturer ID: 0x20, Chip ID: 0xb1
> nand: ST Micro NAND 128MiB 1,8V 16-bit
> nand: 128 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB size: 64
> fsmc-nand 10100000.flash: Using 1-bit HW ECC scheme
> Scanning device for bad blocks
>
> I don't know where or how this happened, I think some change
> in the nand core.

I had a look and honnestly could not find where we broke this. Could it
be possible that it never worked with DT probing and only with platform
data? Any idea of what was the previously working base?

Anyhow, this is just curiosity, patch is relevant (just a little nit
below?).

> Cc: stable@vger.kernel.org
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
>  drivers/mtd/nand/raw/fsmc_nand.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/nand/raw/fsmc_nand.c b/drivers/mtd/nand/raw/fsmc_nand.c
> index df61db8ce466593d533e617c141a8d2498b3a180..154fd9bea3016b2fa7fa720a41ef9eeed6063fd5 100644
> --- a/drivers/mtd/nand/raw/fsmc_nand.c
> +++ b/drivers/mtd/nand/raw/fsmc_nand.c
> @@ -879,7 +879,9 @@ static int fsmc_nand_probe_config_dt(struct platform_device *pdev,
>  		} else if (val != 1) {
>  			dev_err(&pdev->dev, "invalid bank-width %u\n", val);
>  			return -EINVAL;
> -		}
> +		};

                 ^
There is a spurious ';' here, no?

> +	} else {
> +		nand->options |= NAND_BUSWIDTH_AUTO;
>  	}

Thanks,
Miquèl

Re: [PATCH] mtd: rawnand: fsmc: Default to autodetect buswidth

[Linus Walleij]

On Tue, Sep 16, 2025 at 11:33 AM Miquel Raynal
<miquel.raynal@bootlin.com> wrote:
> On 14/09/2025 at 00:35:37 +02, Linus Walleij <linus.walleij@linaro.org> wrote:

> > I don't know where or how this happened, I think some change
> > in the nand core.
>
> I had a look and honnestly could not find where we broke this. Could it
> be possible that it never worked with DT probing and only with platform
> data? Any idea of what was the previously working base?

I tested old kernels back to 4.20 and it didn't work.
Probably it never worked?

I tried to recompile something further back but I don't
have the required old toolchains around :P

> Anyhow, this is just curiosity, patch is relevant (just a little nit
> below?).
> > +             };
>
>                  ^
> There is a spurious ';' here, no?

Fixed in v2, also made a more elaborate handling if someone
would explicitly set the width to 2.

I think the SPEAr that is the primary user always sets the width
to 2 so they never saw this bug.

Yours,
Linus Walleij

Re: [PATCH] mtd: rawnand: fsmc: Default to autodetect buswidth

[Miquel Raynal]

On 16/09/2025 at 20:49:25 +02, Linus Walleij <linus.walleij@linaro.org> wrote:

> On Tue, Sep 16, 2025 at 11:33 AM Miquel Raynal
> <miquel.raynal@bootlin.com> wrote:
>> On 14/09/2025 at 00:35:37 +02, Linus Walleij <linus.walleij@linaro.org> wrote:
>
>> > I don't know where or how this happened, I think some change
>> > in the nand core.
>>
>> I had a look and honnestly could not find where we broke this. Could it
>> be possible that it never worked with DT probing and only with platform
>> data? Any idea of what was the previously working base?
>
> I tested old kernels back to 4.20 and it didn't work.
> Probably it never worked?

Ah :-) Might make sense!

> I tried to recompile something further back but I don't
> have the required old toolchains around :P

Yeah, no pb. As you said, we probably never faced the issue even though
it was latent.

>> Anyhow, this is just curiosity, patch is relevant (just a little nit
>> below?).
>> > +             };
>>
>>                  ^
>> There is a spurious ';' here, no?
>
> Fixed in v2, also made a more elaborate handling if someone
> would explicitly set the width to 2.
>
> I think the SPEAr that is the primary user always sets the width
> to 2 so they never saw this bug.

Certainly.

Thanks!
Miquèl