Re: [PATCH v3] mtd/nand : workaround for Freescale FCM to support large-page Nand chip

LiuShuo a écrit :

于 2011年08月19日 01:00, Matthieu CASTET 写道:

quoted

b35362@freescale.com a écrit :

quoted

From: Liu Shuo<redacted>

Freescale FCM controller has a 2K size limitation of buffer RAM. In order
to support the Nand flash chip whose page size is larger than 2K bytes,
we divide a page into multi-2K pages for MTD layer driver. In that case,
we force to set the page size to 2K bytes. We convert the page address of
MTD layer driver to a real page address in flash chips and a column index
in fsl_elbc driver. We can issue any column address by UA instruction of
elbc controller.

Why do you need to do that ?

When mtd send you a 4k page, why can't you write it by 2*2k pages write ?

1. It's easy to implement.
2. We don't need to move the data in buffer more times, because we
want to use the HW_ECC.

In flash chip per Page:
----------------------------------------------------------------
| first data | first oob | second data | second oob |
----------------------------------------------------------------

How the bad block marker are handled with this remapping ?

Mtd will search in the first oob, but this will be the data zone of the nand,
not where manufacturer put marker.

Matthieu