detect and manage power cut on MLC NAND

[Jeff Lauruhn (jlauruhn)]

Hi Boris; 
> Yes, you are right. This method isn't allowed. User can only program 
> page within a block from low address to high address.

Do you know the reason behind this ?
This is done to help mitigate disturbs and to ensure we get the highest reliability.  Driving software developers crazy is just an extra benefit.  :) 


Jeff Lauruhn
NAND Application Engineer
Embedded Business Unit
Micron Technology, Inc


-----Original Message-----
From: Boris Brezillon [mailto:boris.brezillon at free-electrons.com] 
Sent: Friday, March 20, 2015 8:19 AM
To: Qi Wang 王起 (qiwang)
Cc: Richard Weinberger; Iwo Mergler; linux-mtd at lists.infradead.org; rnd4 at dave-tech.it; Jeff Lauruhn (jlauruhn); dedekind1 at gmail.com; andrea.marson at dave.eu; Bean Huo 霍斌斌 (beanhuo); Frank Liu 刘群 (frankliu); Zoltan Szubbocsev (zszubbocsev)
Subject: Re: detect and manage power cut on MLC NAND

Hi Qi,

On Fri, 20 Mar 2015 15:05:54 +0000
Qi Wang 王起 (qiwang) <qiwang at micron.com> wrote:

> Hi Boris, Richard
> 
> On Fri, 20 Mar 2015 05:08 PM +0000 Richard Weinberger wrote:
> >
> >Am 20.03.2015 um 09:58 schrieb Boris Brezillon:
> >> Hi Qi,
> >>
> >> On Fri, 20 Mar 2015 07:44:58 +0000
> >> Qi Wang 王起 (qiwang) <qiwang at micron.com> wrote:
> >>
> >>>>
> >>>> I seem to remember a requirement to write pages to a block in a 
> >>>> monotonic fashion (low to high). Is that still the case? It seems 
> >>>> that the low page backup could violate that rule otherwise.
> >>>
> >>> Yes, pages need to be programmed from low to high. But it is 
> >>> possible to skip some pages. Take a example,
> >>>
> >>> below page program ordering is ok.
> >>> Page 0, page 1, page 2, page 4, page 6, page 10, page 15, etc..
> >>> Just make sure don't turn back to program the low page is ok.
> >>
> >> I asked a question regarding the programming sequence in answer to 
> >> Iwo, but I'm not sure you were in Cc, so I'm asking it again.
> >>
> >> Say page 1 is paired with page 4, can we program pages in this order:
> >> 1, 4, 2, 5, 3, 6, ..., so that both paired pages are programmed 
> >> together (the Jumbo page approach Iwo described in his mail).
> >
> >That's a good question. I was always told that you're not allowed to 
> >program pages in a non-linear manner.
> >
> 
> Yes, you are right. This method isn't allowed. User can only program 
> page within a block from low address to high address.

Do you know the reason behind this ?



--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com