Re: JFFS2 on NAND flash

[Thomas Gleixner <gleixner@autronix.de>]

On Thursday, 31. January 2002 11:22, David Woodhouse wrote:
> Be careful. You have nothing there to make sure that it doesn't violate the
> constraints on the number of write cycles per page. You have no ECC, you
> have no real chance of it working in the wild.
I know that and i was trying to put a workaround for the write cycle problem 
into the nand driver. I think thats the correct location for this. Are there 
other chips dealing with the same problem or is it related to NAND only ?
My current solutiun would be:
In nand.c the write functions checks the write attempts to a page. If there 
were three writes already to this page, the function reads back the block 
data, erases the block and writes the block data back to the chip. 

Is this also a problem for jffs1 ? I run jffs1 for a couple of weeks on my 
board and had not one problem at all. 

> Also note that the locking in jffs2_garbage_collect_deletion_dirent() is
> broken. We need to lock the erase_completion_lock while we go through the
> list, and drop the lock when we read the nodes.
I'm not deep enough inside this to see the neccecary change. Could you please 
explain more detailed ?

> All the writev stuff was put there for the benefit of NAND flash - so yes,
> nobody's used it yet. This problem had come up recently in the eCos port,
> but the fix hadn't yet propagated to the main tree.
No problem it took only some time to understand what happens there.

Thomas
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Thomas Gleixner, autronix automation GmbH
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