linux-kernel - Re: [PATCH v2 0/3] mtd: Make sure UBIFS does not do multi-pass page programming on flashes that don't support it

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Date:   Fri, 27 Nov 2020 13:55:44 +0100
From:   Richard Weinberger <richard.weinberger@...il.com>
To:     Pratyush Yadav <p.yadav@...com>
Cc:     Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-mtd@...ts.infradead.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/3] mtd: Make sure UBIFS does not do multi-pass page
 programming on flashes that don't support it

On Tue, Nov 24, 2020 at 2:58 PM Pratyush Yadav <p.yadav@...com> wrote:
>
> Hi,
>
> On 18/11/20 11:54PM, Pratyush Yadav wrote:
> > Hi,
> >
> > The Cypress Semper S28 flash family uses 2-bit ECC by default. Under
> > this ECC scheme, multi-pass page programs result in a program error.
> > This means that unlike many other SPI NOR flashes, bit-walking cannot be
> > done. In other words, once a page is programmed, its bits cannot then be
> > flipped to 0 without an erase in between.
> >
> > This causes problems with UBIFS because it uses bit-walking to clear EC
> > and VID magic numbers from a PEB before issuing an erase to preserve the
> > file system correctness in case of power cuts.
> >
> > This series fixes that by setting mtd->writesize to the ECC block size
> > (16) and making sure UBIFS does not try to do a multi-pass write on
> > flashes with writesize > 1.
> >
> > It is based on the xSPI/8D series that adds support for Cypress S28
> > flash [0] (it is in next now). The patches themselves are independent of
> > that series in the sense that they don't rely on 8D support. But since
> > S28 flash is not supported without that series, these patches don't make
> > much sense without it.
> >
> > Tested on Cypress S28HS512T and MT35XU512ABA on J7200 and J721E
> > respectively.
> >
> > [0] https://lore.kernel.org/linux-mtd/20201005153138.6437-1-p.yadav@ti.com/
>
> Any comments on the series? If not, can it be picked up?
>
> > Pratyush Yadav (3):
> >   UBI: Do not zero out EC and VID on ECC-ed NOR flashes
> >   mtd: spi-nor: core: Allow flashes to specify MTD writesize
> >   mtd: spi-nor: spansion: Set ECC block size
> >
> >  drivers/mtd/spi-nor/core.c     | 4 +++-
> >  drivers/mtd/spi-nor/core.h     | 3 +++
> >  drivers/mtd/spi-nor/spansion.c | 1 +
> >  drivers/mtd/ubi/build.c        | 4 +---
> >  drivers/mtd/ubi/io.c           | 9 ++++++++-
> >  5 files changed, 16 insertions(+), 5 deletions(-)

Can we please have am ACK from NOR folks? :-)

-- 
Thanks,
//richard