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Date: Mon, 4 Feb 2013 15:32:20 +0800
From: Huang Shijie <b32955@freescale.com>
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Subject: Re: question about mtd_torturetest.c
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Cc: David Woodhouse <dwmw2@infradead.org>,
 Lin Wei-B34918 <B34918@freescale.com>,
 "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>, "Gupta,
 Pekon" <pekon@ti.com>, Matthieu CASTET <matthieu.castet@parrot.com>
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=E4=BA=8E 2013=E5=B9=B402=E6=9C=8804=E6=97=A5 14:58, Artem Bityutskiy =E5=
=86=99=E9=81=93:
> On Mon, 2013-02-04 at 05:19 +0000, Gupta, Pekon wrote:
>>> On Wed, 2013-01-23 at 15:25 +0800, Huang Shijie wrote:
>>>> Hi all:
>>>>
>>>>      The mtd_torturetest.c uses the 55/AA patterns to torture the na=
nd
>>> block.
>>>> Are the 55/AA patterns more tougher then the random data?
>>> Probably not, please, improve the test.
>>>
>> (0x55/0xAA/0x55) pattern ensures that _all_ bits in the byte transitio=
n from 0->  1, and 1->0,
>> Whereas, a random pattern may miss a bit-cell or miss transition seque=
nce, of an bad bit-cell.
>> Exercising each bit both ways is important so as to differentiate a ba=
d bit-cell (permanent error) from read-disturb errors (temporary error).
>>
>> For read-disturb: http://download.micron.com/pdf/presentations/events/=
flash_mem_summit_jcooke_inconvenient_truths_nand.pdf
> Sure, I did not mean remove those, I meant that random data test can
> also be added and that would be an improvement.
>
I think the random data test is much like the simulation of the nand=20
real use, such as the nand is used in
the filesystem.

thank
Huang Shijie