Messages in this thread | | | From | Masahiro Yamada <> | Date | Wed, 30 Nov 2016 15:09:27 +0900 | Subject | Re: [PATCH 28/39] mtd: nand: denali: move multi NAND fixup code to a helper function |
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Hi Boris,
2016-11-28 1:24 GMT+09:00 Boris Brezillon <boris.brezillon@free-electrons.com>: > On Sun, 27 Nov 2016 03:06:14 +0900 > Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > >> Collect multi NAND fixups into a helper function instead of >> scattering them in denali_init(). > > Can you tell me more about this multi-NAND feature? > The core is already able to detect multi-die NAND chips in a generic > way,
This is not the case.
> but I fear this is something else, like "put two 8-bits chips on a > 16bits bus to emulate a single 16bits chip".
Yes, it is.
(I have never used this controller like that. But, I am pretty sure it is from the code and the Denali's User Guide mentions such usage.)
Just in case, I will clearly rephrase the comment block like follows in v2:
/* * Support for multi device: * When the IP configuration is x16 capable and two x8 chips are * connected in parallel, DEVICES_CONNECTED should be set to 2. * In this case, the core framework knows nothing about this fact, * so we should tell it the _logical_ pagesize and anything necessary. */
> If that's a case, and this feature is actually used, then it's a bad > idea IMHO. > For example, how do you handle the case where one block is bad on a > chip but not on the other? And I fear this is not the only problem > with this approach :-/.
As you expect, if one block is bad, the correspond block on the other chip can not be used.
-- Best Regards Masahiro Yamada
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