Re: JFFS2, AT45DB642D dataflash and power failure

[Ivan Kuten <ivan.kuten@promwad.com>]

On Mon, 4 Jun 2007 08:28:50 +0200
Hans Jorgensen wrote:

> Can JFFS2 handle that an entire flash page gets corrupted if a power
> failure occurs while calling at91_dataflash_write/dataflash_write? If
> not then there might be a problem with
> at91_dataflash.c/mtd_dataflash.c
> 
> The story is as following:
> I am using Linux kernel 2.6.12 + patch 2.6.12 (20/06-2005) from
> maxim.org.za and trying to implement transaction based file access
> with rollback functionality in a user-space application.
> 
> To prove that it would work during power failure I used a watchdog to
> activate reset of the CPU and flashes.  It did not work.
> 
> As an attempt to make it work I modified at91_dataflash_write to use
> the flash commands.
> Buffer 1 Write + Buffer 1 to Main Memory Page Program without Built-in Erase
> instead of
> Main Memory Page Program Through Buffer 1 (which implicit includes an
> erase page functionality)
> 
> Now it is working and that naturally leads to the question above.
> A nice side effect of this change is that writing speed is increased.
> 
> Note: this change may not be a valid solution, as this is not the
> recommended way of using the dataflash. It would require further
> investigation before implementation.
> 
> Hans
> 

Hi Hans,

I had the same problem as you describing with AT91RM9200 and AT45DB642D dataflash,
i tried to ask in this thread http://lists.infradead.org/pipermail/linux-mtd/2007-April/017961.html
but nobody replied.

Could you please post your patch, so I could check if it works for me?

Best regards, 
Ivan