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From:   Richard Weinberger <richard.weinberger@gmail.com>
Date:   Wed, 3 May 2023 21:48:38 +0200
Message-ID: <CAFLxGvwfi2RH3y2M6n0vqUHarp6DwR-wT7oBto3raA7oC3nJvg@mail.gmail.com>
Subject: Re: [PATCH v1 4/5] mtd: rawnand: meson: clear OOB buffer before read
To:     Miquel Raynal <miquel.raynal@bootlin.com>
Cc:     Arseniy Krasnov <avkrasnov@sberdevices.ru>,
        Liang Yang <liang.yang@amlogic.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Kevin Hilman <khilman@baylibre.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        Jianxin Pan <jianxin.pan@amlogic.com>,
        Yixun Lan <yixun.lan@amlogic.com>, oxffffaa@gmail.com,
        kernel@sberdevices.ru, linux-mtd@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org,
        linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
        "yonghui.yu" <yonghui.yu@amlogic.com>
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Sorry for joining the party late.

On Wed, May 3, 2023 at 10:07=E2=80=AFAM Miquel Raynal <miquel.raynal@bootli=
n.com> wrote:
> > So for me main question here is:
> >
> > How JFFS2 should work with controllers where we can't update data and O=
OB
> > independently? Driver of this filesystem knows nothing about this featu=
res of
> > the controller.
> >
> > Or JFFS2 works incorrectly in my case when it tries to call write page =
callback
> > after calling write OOB callback (IIUC it is better to ask Richard as Y=
ou mentioned above).
> >
> > Or may be it is better to suppress OOB write callback (or set it to NUL=
L) in this
> > driver as in vendor's driver?
>
> I would assume using the unprotected free OOB bytes to store the
> cleanmarkers should work. But that's a bit fragile and very filesystem
> oriented. I don't like this much. But on the other side JFFS2 is
> legacy, you should use UBI (which does not play with OOB areas) :-)

Please note that JFFS2's main use case is NOR flash. Support for NAND
flash was never
considered as fully complete/stable. That's why UBIFS (JFFS3 in the
very beginning)
was invented.

Thanks,
//richard