linux-kernel - Re: [PATCH 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:   Tue, 27 Oct 2020 16:48:06 +0530
From:   Pratyush Yadav <p.yadav@...com>
To:     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>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] mtd: Make sure UBIFS does not do multi-pass page
 programming on flashes that don't support it

On 12/10/20 11:34PM, 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 problem by introducing a flag
> MTD_NO_MULTI_PASS_WRITE that tells the file system layer that it can't
> do multi-pass writes. It also sets the writesize to the page size for
> such flashes to make sure file systems know that they should write the
> entire page in one go.
> 
> It is based on the xSPI/8D series that adds support for Cypress S28
> flash [0]. 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/

Ping. Any comments on the series?
 
> Pratyush Yadav (3):
>   mtd: abi: Introduce MTD_NO_MULTI_PASS_WRITE
>   UBI: Do not zero out EC and VID when multi-pass writes are not
>     supported
>   mtd: spi-nor: core: Introduce SPI_NOR_NO_MULTI_PASS_PP
> 
>  drivers/mtd/spi-nor/core.c     | 5 +++++
>  drivers/mtd/spi-nor/core.h     | 6 ++++++
>  drivers/mtd/spi-nor/spansion.c | 2 +-
>  drivers/mtd/ubi/io.c           | 2 +-
>  include/uapi/mtd/mtd-abi.h     | 1 +
>  5 files changed, 14 insertions(+), 2 deletions(-)
> 

-- 
Regards,
Pratyush Yadav
Texas Instruments India