From: Boris Brezillon <bbrezillon@kernel.org>
To: Emil Lenngren <emil.lenngren@gmail.com>
Cc: Marek Vasut <marek.vasut@gmail.com>,
Richard Weinberger <richard@nod.at>,
Boris Brezillon <boris.brezillon@bootlin.com>,
linux-mtd@lists.infradead.org,
Miquel Raynal <miquel.raynal@bootlin.com>,
Brian Norris <computersforpeace@gmail.com>,
David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH] mtd: spinand: Wait after erase in spinand_markbad
Date: Wed, 20 Feb 2019 08:59:17 +0100 [thread overview]
Message-ID: <20190220085917.04f0f47b@kernel.org> (raw)
In-Reply-To: <CAO1O6scHuaGJsS1wXtEpxi930K57yDBUZggb1Sik9XoZMJA+8A@mail.gmail.com>
On Mon, 18 Feb 2019 12:27:25 +0100
Emil Lenngren <emil.lenngren@gmail.com> wrote:
> > > At the same time, it's generally disallowed to write the
> > > same page twice...
> >
> > That's only if you care about the data you write to the page. Marking a
> > block bad is just about setting the BBM to 0x0, which should always work
> > even if the page you're writing to has already been written, simply
> > because a 1 -> 0 cell transition does not require an erase (only a 0 ->
> > 1 transition does).
>
> Should the BBM be written with or without ECC? Now it uses whatever
> mode was used in the last operation. Also for reading, I see the
> "spinand_isbad" function sets .mode to MTD_OPS_RAW but that field
> doesn't seem to be inspected, again using the same ECC mode as in the
> last operation.
> Isn't it best to use the non-ECC mode for both reading and writing the
> BBM?
We should definitely disable the ECC engine when reading/writing the
BBM.
> If we would use ECC mode and overwrite the page when writing the
> BBM marker, I guess the controller needs to store a second error
> correction code (overwriting the previous one), which will probably
> lead to ECC failure if later read in ECC-mode (and who knows if it
> will "correct" the zero bits to ones...).
Well, you could just ignore the ECC result, but that's better to simply
read the BBM in raw mode.
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next prev parent reply other threads:[~2019-02-20 7:59 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-21 11:58 [PATCH] mtd: spinand: Wait after erase in spinand_markbad Emil Lenngren
2019-01-05 13:58 ` Boris Brezillon
2019-01-06 6:01 ` Emil Lenngren
2019-01-06 8:10 ` Boris Brezillon
2019-02-18 11:27 ` Emil Lenngren
2019-02-20 7:59 ` Boris Brezillon [this message]
2019-03-04 11:23 ` Miquel Raynal
2019-03-04 11:55 ` Emil Lenngren
2019-03-04 12:50 ` Miquel Raynal
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