[PATCH] Fixup for Numonyx M29W128 chips

[Darius Augulis]

massimo cirillo wrote:
> Hi ,
> We performed a complete validation test session on this device,
> using jffs2 in the 2.6.26.1 release kernel, without any failures.
> Could you specify the test case and the related failure?
> What kernel version did you use? Did you apply any patch?
> Thanks,
> Massimo

Hi,

I use newest 2.6.29 kernel. The same was with 2.6.28.
My flash device is M29W128GL.
This is the sequence how writing to flash crashes:

1. Mount new and fresh (empty) jffs2 partition.
2. Create emtpy file ("touch test")
3. Echo short string to this file ("echo test > test")
4. Unmount partition (optional)
5. Reboot system
6. Mount the same jffs2 partition
7. Create another file ("touch test2")
8. Try to write something to this file ("echo test > test2")
9. Get this error: [42949481.440000] Node totlen on flash (0xffffffff) != totlen from node ref (0x00000044)
10. Unmount and reboot
11. Get jffs2 errors and broken file system:

starting pid 37, tty '': '/bin/mount -t jffs2 /dev/mtdblock3 /tmp/cfg'
[42949376.530000] Empty flash at 0x0000415c ends at 0x00004180
[42949376.550000] jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00004180: 0xe3db instead
[42949376.580000] jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00004184: 0xe3db instead
[42949376.600000] jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0000419c: 0x2452 instead


There absolutely no problem if write buffer is disabled.
So I don't guess this is hardware error. May it be memory chip defect?

Darius.





> 
> 2009/3/26 Darius Augulis <augulis.darius at gmail.com>:
>> Hi,
>>
>> I'm getting jffs2 errors after write to flash. I don't have the output log
>> now, but the idea is that after write to flash, jffs2 does not find magic
>> numbers anymore. File system is broken.
>> It's completely resolved when write buffers are not used. I could make patch
>> which disables write buffer only for M29W128 chips. Anyway it's not working,
>> one who needs more performace, is welcome to fix this in better way...
>>
>> Darius.
>>
>> massimo cirillo wrote:
>>> Hi Darius,
>>> what kind of failure did you experiment with M29W?
>>>
>>> In my opinion, complete removal of the buffer program feature is not a
>>> good solution,
>>> because you are taking away an important feature of the device, that
>>> results in
>>> a very high performance decrease.
>>>
>>> Moreover, if you make the fix applicable to all devices with 0x227E device
>>> ID,
>>> you are removing the same feature from other devices too, such as M29EW
>>> that has a much bigger buffer thus resulting in a dramatic performance
>>> decrease
>>> for this device.
>>>
>>>
>>
> 
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