On 01/11/2013 02:46:06 AM, Dimitar Penev wrote:
Hi Scott,
On 01/10/2013 01:56:30 AM, Dimitar Penev wrote:
Hello,
First of all sorry if this question was already answered here.
We are sourcing some K9F8G08U0M-PIB0 NAND flash devices.
On the first erase in uboot 2011.09 I got bunch of mostly
consecutive bad blocks.
According to the datasheet we should get not more then 80 bad
blocks for our chip
but I get something like 240 bad blocks for most of the NAND chips.
I seems to be able to fix this using the following procedure:
Call your NAND vendor and complain?
Well we did but we didn't got something from them which could explain
what we observe.
After making sure that there's nothing wrong with your NAND driver
or controller that causes the OOB to be read incorrectly.
We are using nand_plat driver provide by ADI without any
customization.
Still, do some investigation to see whether it seems to be working.
Dump the raw data that you read -- is it mostly 0xff with some bad
block markers set, or is it returning garbage? Do any of the blocks
that are not marked bad have non-0xff data? If you do a scrub of the
entire NAND chip, then write to one block, does the write show up
anywhere else on the NAND chip?
In uboot
uboot>nand scrub.chip
In uboot
uboot>nand erase.chip clean
at this point I get usually 1,2 bad blocks which looks normal to me.
You're not fixing anything -- you're wiping out all bad block
information. Those "1,2 bad blocks" are not actually bad blocks,
but are the bad block table which appears "bad" to reserve it.
These should be at the end of flash. Or, possibly, they're blocks
that happen to be damaged in a way that prevents the bad block
marker from becoming 0xff.
Oh Really?
What about 'nandtest -m' in Linux ? I was hoping it does a check of
the erase blocks.
That's no substitute for having the factory bad block markers.
Nandtest doesn't look very rigorous at all -- and only seems to mark
bad blocks if the erase or write operations return failure, not if it
sees an uncorrectable error on readback.
Thanks Scott.
Is there any procedure to analyze the nand flash for bad blocks?
Yes, and it's done by the flash manufacturer to produce bad block
markers. :-P
-Scott
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