Problems with AMD CFI chips

[mark.langsdorf at amd.com]

> mark.langsdorf at amd.com said:
> >  The Flash bank is found correctly, and loads, and I can 
> > write to it.
> > However, when I boot from it, I can't seem to get it to 
> > commit writes- either creating new files or altering old
> > ones.  Once I reboot the device, my changes are gone.
> 
> Please check using the /dev/mtd0 device directly to see 
> whether your writes are 'taking'. 

	I can write to /dev/mtd0, the writes through the char
interface are definitely consistent over power-outs.  It's
only when I use jffs on /dev/mtdblock0 that I run into problems.

> What 'map' driver are you using?

	Modified version of physmap, since the flash banks are
physically mapped at 0x2000000 but I needed to partition them
because the BIOS and kernel image are also stored on the same
banks.

> for me on the iPAQ because I wasn't enabling the Vpp voltage
> during write cycles. Is this necessary on your targer?
> 
> Other than that, poke the author and/or look at the code 
> yourself to see what's happening. What interleave/buswidth
> are you using?

	Interleave 2, 4 byte buswidth, to support 2 16 bit chips.
Again, that all looks pretty consistent.

	I think it may be some kind of interaction with jffs,
because I've had limited success with creating directories 
and deleting files, but not consistently.  I'm not sure where
I should look in the jffs code to get more information, though,
and would appreciate some pointers.
	Also, when does jffs attempt to clean out the dirty
space?  thread_should_wake reports upwards of 2 megs of
dirty space, which is about 16 sectors and 14% of the available
memory.  I'd think that should get returned to the free list
much earlier, especially during the reboots.

-Mark Langsdorf
AMD, Inc.


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