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Subject: Re: Numonyx NOR and chip->mutex bug?
Message-ID: <OF1160F22A.C6961712-ONC1257833.00526535-C1257833.0052DAD1@transmode.se>
From: Joakim Tjernlund <joakim.tjernlund@transmode.se>
Date: Thu, 10 Feb 2011 16:04:59 +0100
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Cc: linux-mtd-bounces@lists.infradead.org, stefan.bigler@keymile.com,
	Michael Cashwell <mboards@prograde.net>, linux-mtd@lists.infradead.org,
	=?ISO-8859-15?Q?Anders_Grafstr=F6m?= <grfstrm@users.sourceforge.net>,
	Holger brunck <holger.brunck@keymile.com>
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>
> Anders Grafström <grfstrm@users.sourceforge.net> wrote on 2011/02/10 14:21:36:
> >
> > On 2011-02-09 22:59, Michael Cashwell wrote:
> > > On Feb 9, 2011, at 3:13 PM, Joakim Tjernlund wrote:
> > >
> > >> hmm, this sounds similar(from http://www.numonyx.com/Documents/Specification%20Updates/SU-309045_P30.pdf)
> > >>
> > >> 5. W602: erase suspend resume operation
> > >> Problem: P30 product may fail to erase in intensive erase/suspend/resume environments. This is
> > >>        due to an internal firmware issue that is exhibited in certain applications that require at
> > >>       least 3000 to 4000 erase/suspend/resume cycles during the erase of a single block.
> > >> Implication: Customer may see erase failure (SR reports “A0”) during a background erase. This
> > >>                does not damage the device in any way, but data in the block may be disturbed from its
> > >>               original state.
> >
> > I've seen this issue with Intel 28F640J5 chips as well.
> >
> > There's an old thread on it.
> > http://lists.infradead.org/pipermail/linux-mtd/2008-April/021266.html
> >
> > A delay was suggested similar to the one you're experimenting with I think.
> > http://lists.infradead.org/pipermail/linux-mtd/2008-April/021436.html
>
> Oh, I had forgotten about this thread :)
>
> I agree with the latency theory, for Numonyx there is this:
>
> W602 is the typical time between an initial block erase or erase resume command and the a subsequent erase suspend
> command. Violating the specification repeatedly during any particular block erase may cause erase failures.
>
> W602 is defined to 500us
>
> Adding a delay after resume will do it but is a bit crude. Possibly one
> could add a timestamp at resume/initial erase and a check in suspend that enough time has passed
> before suspending again.
>
> How does that sound?

A simpler impl. would be a suspend counter. When no. of suspends > 1000, do usleep(500)
or usleep(500) every 100-500 suspends.

 Jocke