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From: Miquel Raynal <miquel.raynal@bootlin.com>
To: "Wojtaszczyk, Piotr" <WojtaszczykP@cumminsallison.com>,
	Bean Huo <beanhuo@micron.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Tudor Ambarus <Tudor.Ambarus@microchip.com>,
	Zoltan Szubbocsev <zszubbocsev@micron.com>,
	Richard Weinberger <richard@nod.at>,
	Boris Brezillon <boris.brezillon@collabora.com>,
	"linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>
Subject: Re: [RFC PATCH 0/3] Fix proposal for the Micron shallow erase issue
Date: Sun, 3 May 2020 13:29:13 +0200	[thread overview]
Message-ID: <20200503132913.40b739a3@xps13> (raw)
In-Reply-To: <c2bf2161-7122-4d59-3e51-57db27654685@cumminsallison.com>

Hi Bean,

There are two technical questions below that I would like you to answer.

> >>> Also after power loss all flags in micron->writtenp are gone so the
> >>> micron_nand_avoid_shallow_erase will perform on all PEBs causing performance loss.  
> >>
> >> Yes, that's a performance hit we'll have to accept for now.
> >>  
> > 
> > This is quite severe issue, this is the best idea we came with to
> > limit performance hits.  
> 
> This will be an issue on devices which restarts quite often, what if we read OOB of middle 
> page of the block we are about to erase and if it has all 0xff the it means it is 
> partially programmed and needs the quirk. It's reading 64/128 bytes (depending on NAND 
> size) before every erase versus programming 8 pages on each PEB erase once per device restart.
> 
> Also I know by speaking with Micron that programming 0 in spare area is enough and 
> actually we should program 8 even/odd pages starting from middle of PEB. In case PEB has 
> 64 pages we should program OOB of page 31,33,35,37,39,41,43,45 or 32,34,36,38,40,42,44,46
> Can somebody from Micron confirm that?

So the questions are:

1/ What should we write exactly:
    -> the main area
    -> the OOB area
    -> both
   ?

2/ Shall we prefer writing 8 even/odd pages starting from:
    -> the beginning of the
    -> the middle of the block
    -> we do not care
   ?

Thanks,
Miquèl

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  reply	other threads:[~2020-05-03 11:29 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-31 19:26 [RFC PATCH 0/3] Fix proposal for the Micron shallow erase issue Miquel Raynal
2019-12-31 19:26 ` [RFC PATCH 1/3] mtd: rawnand: Add the nand_chip->erase hook Miquel Raynal
2019-12-31 19:26 ` [RFC PATCH 2/3] mtd: rawnand: Add the nand_chip->write_oob hook Miquel Raynal
2019-12-31 19:26 ` [RFC PATCH 3/3] mtd: rawnand: micron: Address the shallow erase issue Miquel Raynal
2020-01-02 18:41 ` [RFC PATCH 0/3] Fix proposal for the Micron " Florian Fainelli
2020-01-14  9:12   ` Miquel Raynal
2020-01-14 20:46     ` Wojtaszczyk, Piotr
2020-01-15  7:58       ` Boris Brezillon
2020-01-15  8:13         ` Miquel Raynal
2020-01-15 16:51           ` Wojtaszczyk, Piotr
2020-05-03 11:29             ` Miquel Raynal [this message]
2020-05-04  8:08               ` [EXT] " Bean Huo (beanhuo)
2020-05-04  8:26                 ` Miquel Raynal
2020-05-06 15:36                   ` Bean Huo (beanhuo)

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