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Subject: Re: Numonyx NOR and chip->mutex bug?
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From: Michael Cashwell <mboards@prograde.net>
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To: Joakim Tjernlund <joakim.tjernlund@transmode.se>
Cc: linux-mtd@lists.infradead.org, stefan.bigler@keymile.com,
	Holger brunck <holger.brunck@keymile.com>,
	=?iso-8859-1?Q?Anders_Grafstr=F6m?= <grfstrm@users.sourceforge.net>
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Anders Grafstr=F6m <grfstrm@users.sourceforge.net> wrote on 2011/02/10 =
14:21:36:

> It produced this output at one occasion:
>=20
> 6000 loops
> status 00800080
> ffff0000
> ffff0000
> 4783 suspends
> ---------------------
> See the status 00800080 ?
> Looking at the code this should not be possible, right?


It's similar but not identical to my issue. I was seeing a buffered =
programming operation (done while an erase was suspended) appear to fail =
because the status read looking for program completion would return =
garbage. Your case is only erase, not programming.

But yours looks similar to mine in that your resumed erase completes =
(00800080) and then the next several status read returns garbage. =
Interestingly, the low chip returns correct status (WSM busy, nothing =
suspended, no errors, etc.) but the high chip returns FFFF. That was =
often what mine did during buffer program.

I also sometimes would see other values, not always FFFF. But with bits =
set in the upper byte whatever was being read was clearly NOT status. =
Since FFFF is correct for erased array data I assumed the part had =
dropped out of status-read mode but I've not been able to determine why.

Also, on my parts there is a loose restriction on the minimum time =
between starting or resuming an erase and the next suspend of it. It's =
500=B5s for my part and they say that "repeated violations" of that time =
can cause erase failures. The hard part is that the 500=B5s is only a =
typical value and no hard number is given for how many violations are =
needed to cause a failure. I suspect it varies from part to part.

Your code suspends immediately after starting the erase, so that would =
be a violation on my part. And depending on the value of loops you might =
be violating it often.

On Feb 24, 2011, at 6:36 AM, Joakim Tjernlund wrote:

> Michael, have you made any progress?

Sadly, management was breathing down my neck to get it working and I've =
been pulled completely off onto a different project. I do still want to =
find the real answer but currently the people who control the purse =
strings have other ideas. There is another board in the pipeline here =
that might have this part on it. When that arrives on my desk I'll see =
if I can pick this up again.

> Can you run Anders program too?

Not as written. My board only has one flash chip where Anders' clearly =
has two chips in parallel. It wouldn't be too hard to change it to =
1-wide but I'm overloaded on my other project at present.

-Mike