linux-kernel - Re: [PATCH v4 1/2] mtd: spi-nand: Add support for randomizer

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Message-ID: <CAAyq3SbZn5Hjx85xMS4cPYaoBccsiCj1obRbLO9eD9_RV=h7RQ@mail.gmail.com>
Date: Wed, 4 Feb 2026 09:47:15 +0800
From: Cheng Ming Lin <linchengming884@...il.com>
To: Miquel Raynal <miquel.raynal@...tlin.com>
Cc: Vignesh Raghavendra <vigneshr@...com>, Richard Weinberger <richard@....at>, 
	Tudor Ambarus <tudor.ambarus@...aro.org>, Martin Kurbanov <mmkurbanov@...utedevices.com>, 
	Mikhail Kshevetskiy <mikhail.kshevetskiy@...sys.eu>, Pratyush Yadav <pratyush@...nel.org>, 
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	alvinzhou@...c.com.tw, Cheng Ming Lin <chengminglin@...c.com.tw>
Subject: Re: [PATCH v4 1/2] mtd: spi-nand: Add support for randomizer

Hi Miquel,

Miquel Raynal <miquel.raynal@...tlin.com> 於 2026年2月3日週二 下午10:40寫道：
>
> Hello Cheng Ming,
>
> On 03/02/2026 at 10:13:57 +08, Cheng Ming Lin <linchengming884@...il.com> wrote:
>
> > From: Cheng Ming Lin <chengminglin@...c.com.tw>
> >
> > This patch adds support for the randomizer feature.
> >
> > It introduces a 'set_randomizer' callback in 'struct spinand_info' and
> > 'struct spinand_device'.
> >
> > If a driver implements this callback, the core will call it during
> > device initialization (spinand_init) to enable the randomizer.
>
> I recently had a request regarding the sunxi controller driver
> randomizer. I would like to get back to having a nand wide randomizer DT
> property, because a Macronix specific value honestly no longer makes
> sense. Randomizers have been there for ages, they are not so often used
> because scrambling data is not convenient for developers but they may
> have a real interest depending on the NAND chip or the external
> conditions.
>
> We will need two mutually exclusive optional properties in
> nand-chip.yaml:
> nand-enable-randomizer;
> nand-disable-randomizer;

Agreed. It makes sense to switch to generic device tree properties as
you suggested.

I will introduce nand-enable-randomizer and nand-disable-randomizer
in nand-chip.yaml.

In addition, I will also update the Macronix raw nand flash driver to use
these generic randomizer properties for consistency.

>
> BTW, where is the patch adding the property to the bindings? Did we
> already merge it? I do not find it anymore.

It has not been merged yet. Since the current patch series uses the
vendor-specific property "mxic,randomizer-enable", I did not include a
patch to update the generic bindings.

I will include a new patch in v5 to add these properties to
nand-chip.yaml.

>
> Looking at the current implementation, I really don't like the core
> always calling in the "init" and the manufacturer driver reading the DT
> and deciding whether or not it enables it.

I agree. I will refactor the logic in v5 so that the core parses the
generic DT properties (nand-enable-randomizer and
nand-disable-randomizer).

Then, spinand_randomizer_init will determine the state and pass a
boolean argument to the set_randomizer callback, leaving the driver
to strictly handle the hardware configuration.

>
> > Signed-off-by: Cheng Ming Lin <chengminglin@...c.com.tw>
> > ---
> >  drivers/mtd/nand/spi/core.c | 23 +++++++++++++++++++++++
> >  include/linux/mtd/spinand.h |  9 +++++++++
> >  2 files changed, 32 insertions(+)
> >
> > diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> > index d207286572d8..4f8ff94f5ccc 100644
> > --- a/drivers/mtd/nand/spi/core.c
> > +++ b/drivers/mtd/nand/spi/core.c
> > @@ -206,6 +206,12 @@ static int spinand_cont_read_enable(struct spinand_device *spinand,
> >       return spinand->set_cont_read(spinand, enable);
> >  }
> >
> > +static int spinand_randomizer_enable(struct spinand_device *spinand,
> > +                                  bool enable)
> > +{
> > +     return spinand->set_randomizer(spinand, enable);
>
> This helper seems mostly useless.
>
> > +}
> > +
> >  static int spinand_check_ecc_status(struct spinand_device *spinand, u8 status)
> >  {
> >       struct nand_device *nand = spinand_to_nand(spinand);
> > @@ -1218,6 +1224,19 @@ static int spinand_create_dirmaps(struct spinand_device *spinand)
> >       return 0;
> >  }
> >
> > +static int spinand_randomizer_init(struct spinand_device *spinand)
> > +{
> > +     int ret;
> > +
> > +     if (spinand->set_randomizer) {
> > +             ret = spinand_randomizer_enable(spinand, true);
>
> Please directly call the hook.
>
> Given the previous feedback, you should change "true" to be based on the
> presence of the DT property.
>
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +
> > +     return 0;
> > +}
>
> Rest LGTM.
>
> Thanks,
> Miquèl

Thanks,
Cheng Ming Lin