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Sorry to take so long to get back to you - busy week. Anyway, the docs you pointed me to are for the processor alone, which while it is an ...
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  1. #11
    Linux Guru Rubberman's Avatar
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    Sorry to take so long to get back to you - busy week. Anyway, the docs you pointed me to are for the processor alone, which while it is an SOC (System On Chip) with most everything you want, you haven't provided me with anything on your actual board. I assume you purchased a development/prototype board from somewhere, or did you design/build it yourself?
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

  2. #12
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    Yes that is correct.We purchased the evaluation/development board from third party.
    The evaluation board was PXA255 processor based. Then our hardware designer designed it for PXA270 and sent us directly the prototype board.

    Then we ported linux kernel 2.6.19-1, we ported one nand flash driver and wrote some other drivers for target platform. Hence I don't have the actual documentation that you might be interested in. I also went through this link: Memory Technology Device (MTD) Subsystem for Linux.
    The link mentions that if you are encountering errors viz. "jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found" means that data on your flash device is not valid JFFS2 file system. In my case the function causing the error is same but it shows "jffs2_scan_eraseblock(): Invalid CRC", so I though I might consider this.
    And it also mentions 4 reasons this could be happening.

    1. you flash driver is severely buggy so it reads trash instead of valid data;
    [Sumit]: It could be. How to debug it?
    2. you flashed some trash instead of a valid JFFS2 image;
    [Sumit]: The file system is flashed only once. Afterwards, application reads/writes data on files present on flash. I create file system using mkfs.jffs2 utility and flashed it using tftp and cp.b commands on target board.
    3. you did not manage to flash JFFS2 image correctly so that you ended up with garbage on your flash, although the original image was perfectly fine;
    [Sumit]: How to debug it?
    4. you forgot to erase your flash before flashing it, etc.
    [Sumit]: No, I did not.

    Also as per 4th FAQ on that link "JFFS2 generates messages, is there a problem?", I upgraded my mkfs.jffs2 utility, but with no difference in observation.

    Let me know if you need additional information. I would like to mention that, our product does not have a shutdown option, its just abrupt power off, that does not cause "halt" or "shutdown" commands to execute at the back end.

    ---Sumit
    Last edited by sumitv; 12-10-2010 at 03:02 PM.

  3. #13
    Linux Guru Rubberman's Avatar
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    I don't suppose the board implements the jtag debugging interface and that you have the appropriate hardware/software tools to use it? That is typically what you need to suss this sort of stuff out. That, or a good ICE (in-circuit emulator). I think the jtag specifications were intended to avoid needing a different ICE for every board you make. Sorry, but I am at a dead-end at this point. I haven't had to get into board-level debugging like this for about 20 years, so everything I used to know is somewhat dated, defunct, and not very useful.

    So, usually I would call in a specialist at this point. Co$t$ big $$... but you usually don't need them around more than a few days. After banging your head for months, it would probably be a reasonable investment. Check on the IEEE web site. They have a directory of consulting engineers and their skills that you can search to find an appropriate resource in case you don't have one available.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

  4. #14
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    Yes, my board does have JTAG interface and I have already tried that. But I did not get much information to debug further.

    I may need to think of your suggestion. Off course, that will also take some time.
    Thanks for your help. I have sent you a friend request .

    ---Sumit

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