Combining multiple NAND MTDs

Combining multiple NAND MTDs

[Barry G]

Hello,

I have an 8308 using the fsl_elbc_nand NAND controller.  I have
chip selects 2 & 3 hooked up to a single die multiple chip select NAND
chip.  I have programmed u-boot and the kernel correctly and the
NAND "chips" are found:
NAND device: Manufacturer ID: 0xec, Chip ID: 0xd3 (Samsung NAND 1GiB
3,3V 8-bit)
eLBC NAND device at 0xe0600000, bank 1
NAND device: Manufacturer ID: 0xec, Chip ID: 0xd3 (Samsung NAND 1GiB
3,3V 8-bit)
eLBC NAND device at 0xe0608000, bank 2

The nand chips are correctly show up:
# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 02000000 00020000 "fe000000.flash"
mtd1: 40000000 00020000 "e0600000.flash"
mtd2: 40000000 00020000 "e0608000.flash"

(mtd0 is unrelated NOR part).

I want to run UBIFS on the combined 2 gigs of flash.  Whats the best
way to do this?

I tried using the mtdconcat stuff and wrote a small driver
but I am not sure how to populate the mtd_info structure since do_probe_map
doesn't work with NAND AFAIK.

I see that fsl_elbc_select_chip says "hardware does not seem to support this".
Not sure if this is related.

I see some comments in mtd-physmap.txt about using multiple reg ranges?
Does this work with NAND?

Thanks for any pointers,

Barry

Re: Combining multiple NAND MTDs

[Scott Wood]

On Tue, 5 Apr 2011 16:35:10 -0700
Barry G <mr.scada@gmail.com> wrote:

> I want to run UBIFS on the combined 2 gigs of flash.  Whats the best
> way to do this?
> 
> I tried using the mtdconcat stuff and wrote a small driver
> but I am not sure how to populate the mtd_info structure since do_probe_map
> doesn't work with NAND AFAIK.
> 
> I see that fsl_elbc_select_chip says "hardware does not seem to support this".
> Not sure if this is related.

It's not related -- it's talking about a single physical chip with
multiple chip selects, not a logical concatenation of multiple separate
devices.

> I see some comments in mtd-physmap.txt about using multiple reg ranges?
> Does this work with NAND?

No.

I don't know of an out-of-the-box configuration step you can take to do
mtdconcat of eLBC NAND, but you could try creating a custom map driver that
glues things together as you wish.  Or if you want to be more ambitious,
perhaps a kernel command line (or other dynamic config) option that lets you
glue arbitrary MTD devices together.

-Scott