SPI DataFlash interfacing using 2.4.26

Hi all,

Did anyone on the group sucessfully interfaced a JFFS2
partition on SPI DataFlash on Atmel's AT91RM9200 DK using kernel 2.4.26 ? I have been able to mount the partition but read/write was giving CRC errors. If anyone has been able to do it succesfully please let me know your setup and what are the steps that you followed ?

Thanx
Narinder

hi Narinder,

I'm running JFFS2-on-DataFlash successfully on 2.4.27-vrs1.

1) You will need to download the latest CVS version of the MTD/JFFS2 code from cvs.infradead.org (see http://www.linux-mtd.infradead.org/ for instructions).

2) Read the INSTALL file and then run the ./patchin.sh script

3) There are some incompatibilities with 2.4 kernels, but they're not difficult to fix. This might help:
http://lists.infradead.org/pipermail/linux-mtd/2004-December/011039.html

4) Configure your kernel and enable "JFFS2 write-buffering support" under Filesystems->JFFS2.

Regards,
Andrew Victor

Dear Mr. Andrew,

I tried out the solution that you mentioned in the last
mail (please look into the mail below) but still i am not able to reach at a safe state. It did helped a bit in the sense that now my flash code recovers from CRC errors sometimes but sometimes it fails too and it fails because of Data corruption and when it fails it aborts my application and thereafter i have to start from the beginning i.e erasing the flash completely and then putting the application again.

Can you please guide me in a bit detailed manner ? Which version of MTD is being used by you ?

I tried out mtd-snapshot-20050217.tar and latest one also but still not able to get rid of my problem.
I installed mtd using patchin.sh script with "-c -j" options and i copied an older version(1.60) of mtdchar.c file as the newer one was giving errors during kernel compilation and when i replaced it with older version mtdchar then the kernel compiled succesfully.
If there is something crucial that i am missing out please let me know. I hope you have not done any major changes in the patches itself to get it working, if that is the case can you please update me where from can i get the working patches for 2.4.27-vrs1 or if you can forward the patches to me , that will be great.

Regards,
Narinder

hi Narinder,

Sorry for the late reply.

Either of those should work - the DataFlash support was merged before then.

There is one item I think I forgot to mention.

In the at91_dataflash.c driver, change the line:

    device->type = MTD_NORFLASH;
to
    device->type = MTD_DATAFLASH;

Then also make sure you have "JFFS2 write-buffering support" enabled in the configuration. (It's under the File Systems menu).

You should see the message "JFFS2 write-buffering enabled" printed to kernel log when you mount the partition. If you don't see it, the Dataflash support is not correctly enabled.

Regards,
Andrew Victor