Messages in this thread | | | Date | Sun, 12 Jun 2016 17:10:15 +0200 | From | Boris Brezillon <> | Subject | Re: [PATCH 2/4] mtd: nand: implement two pairing scheme |
| |
On Sun, 12 Jun 2016 14:42:15 +0200 Boris Brezillon <boris.brezillon@free-electrons.com> wrote:
> > > > >> Also, the data sheets are a real PITA to find. I have yet to > > >> see an actual data sheet that documents the stride-3 pairing scheme. > > > > > Yes, that's a real problem. Here is a Samsung NAND data sheet > > > describing stride-3 [1], and an Hynix one describing stride-6 [2]. > > > > > > [1]http://dl.btc.pl/kamami_wa/k9gbg08u0a_ds.pdf > > > [2]http://www.szyuda88.com/uploadfile/cfile/201061714220663.pdf > > > > Thank you very much! > > > > Did you see the footnote at the bottom of p. 64 of the latter? > > Does that affect your pair/group addressing scheme? > > > > It seems they are grouping not just 8K pages into even/odd double-pages, > > and those 16K double-pages are being addressed with stride of 3. > > > > But in particular, an interrupted write is likely to corrupt both > > double-pages, 32K of data! > > Yes, that's yet another problem I decided to ignore for now :).
Now I remember why I decided to ignore this. If you look at this other Hynix data sheet [1] exposing the same pairing scheme you see that the description as slightly changed. I don't know if it's a fix from the previous description or if the pairing scheme are really different, but until someone has tested it on a real device, I'll assume the Hynix case is an exception which should be handled separately.
> > I guess a solution would be to consider that all 4 pages are 'paired' > together, but this also implies considering that the NAND is a 4-level > cells, which will make us loose even more space when operating in 'SLC > mode' where we only write the lower page (page attached to group 0) of > each pair. >
[1]http://minipcsale.ru/images/joomlakassa/TV_BOX/MINIX_NEO_X7/SK%20Hynix%20H27UCG8T2BTR.pdf
-- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
| |