spanning multiple chips with one mtd device

spanning multiple chips with one mtd device

[Andrew Dixon]

Hi All,

I've got a board here with two strataflash chips that are contiguous in
memory.  I'd like linux to use as one mtd device.  I've kind of got it
to kind of work by faking out cfi_chip_setup in cfi_probe.c.  I just
increase cfi->cfiq->DevSize by one so that it thinks the device is twice
as big and then I add one to cfi->cfiq->NumEraseRegions so that it
thinks that there are two erase blocks (each one being one of my flash
chips).

This device is happily recognized and I can mount it as a jffs2 on
/mnt.  It even works as long as I don't write too much data to it.  When
I try to write enough data so that it should access the other flash chip
I run into problems.  The write seems to go OK and the data looks good
but if I unmount and remount the partition all of the data is lost and
I've got an empty filesystem.  If I've only written a few small files I
can unmount and remount without problem.

If anyone has any hints, tips or pointers for me I'd really appreciate
it.

Thanks,
Andy


--
Andrew Dixon
Software Engineer
Seranoa Networks
978.897.3434 x231

spanning multiple chips with one mtd device

[Andrew Dixon]

Hi All,

I've got a board here with two strataflash chips that are contiguous in
memory.  I'd like linux to use as one mtd device.  I've kind of got it
to kind of work by faking out cfi_chip_setup in cfi_probe.c.  I just
increase cfi->cfiq->DevSize by one so that it thinks the device is twice
as big and then I add one to cfi->cfiq->NumEraseRegions so that it
thinks that there are two erase blocks (each one being one of my flash
chips).  

This device is happily recognized and I can mount it as a jffs2 on
/mnt.  It even works as long as I don't write too much data to it.  When
I try to write enough data so that it should access the other flash chip
I run into problems.  The write seems to go OK and the data looks good
but if I unmount and remount the partition all of the data is lost and
I've got an empty filesystem.  If I've only written a few small files I
can unmount and remount without problem.

If anyone has any hints, tips or pointers for me I'd really appreciate
it.

Thanks,
Andy

 
-- 
Andrew Dixon
Software Engineer
Seranoa Networks
978.897.3434 x231

Re: spanning multiple chips with one mtd device

[Jörn Engel]

Hi!

> [yet another approach]
> 
> If anyone has any hints, tips or pointers for me I'd really appreciate
> it.

You have create the fourth solution for the same problem - as far as I
am aware of it. Search for Aleksander Sanochkin or Robert Kaiser on
the list.
The general problem is concatenating two partitions, your problem is
merely a subset thereof.

Jörn

-- 
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