NAND Flash ECC

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suzyq
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Posted by suzyq: Thu. Apr 30, 2009 - 12:51 PM
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Hi,

I want to use a 8Gb Micron NAND Flash (MT29F8G08AAAWP) in a design.
The AT32AP7000 datasheet states, that the ECC controller only supports NAND chips with 528, 1056, 2112 and 4224 bytes page size.
The Micron NAND has 4314 bytes page size.
I therefore assume that I cannot use hardware ECC with this NAND chip.

Would software ECC from the kernel work with this Micron NAND?

What is the impact in using software ECC?
Just speed?

Gerhard

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AVR Microcontrollers, AVR UC3, AT32AP7000
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squidgit
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Posted by squidgit: Fri. May 1, 2009 - 07:41 AM
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suzyq wrote:
I therefore assume that I cannot use hardware ECC with this NAND chip.
I believe so :-(
Quote:
Would software ECC from the kernel work with this Micron NAND?
Sure
Quote:
What is the impact in using software ECC?
Just speed?
Pretty much, yeah. Though it can be a lot of speed. A real lot of speed. If you use an ecc-aware filesystem like yaffs2, jffs2 or (i believe) ubifs then things won't be too bad. Though what you'd be doing running jffs2 on an 8G flash I donno, best stick to yaffs2 or ubifs. If you've got a database on there -> pain. If you're running apps off there -> make sure you've got lots of RAM and you should be OK. If you're just using it for log files or similar -> win!

-S.

Blag: http://www.niasdigital.com/blag

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eaanon01
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Posted by eaanon01: Fri. May 1, 2009 - 12:50 PM
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The decrease in speed from HW to SW ecc has been a reduction of 33% in my case..

Life's to short for waiting on slow CPU's

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suzyq
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Posted by suzyq: Fri. May 1, 2009 - 07:03 PM
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... thanks guys for your help!
It will be used for a low-frequency data logging application.
I think that I'm going to use software ECC, possibly with yaffs2 or ubifs.

Gerhard

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eaanon01
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Posted by eaanon01: Fri. May 1, 2009 - 08:34 PM
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I use UBI/UBIFS with great sucess...

Life's to short for waiting on slow CPU's

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squidgit
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Posted by squidgit: Sat. May 2, 2009 - 10:08 AM
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my $0.02 there is that ubifs is upstream meaning
1) more reviewed
2) prolly better thought out
3) gonna be maintained for ages
4) don't need to try and patch anything

yaffs2 isn't.

-S.

Blag: http://www.niasdigital.com/blag

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