* [U-Boot] NAND flash - bad blocks
@ 2013-01-10 7:56 Dimitar Penev
2013-01-10 19:19 ` Scott Wood
0 siblings, 1 reply; 6+ messages in thread
From: Dimitar Penev @ 2013-01-10 7:56 UTC (permalink / raw)
To: u-boot
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:
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.
In Linux we have few mtd partitions on this NAND chip.
Unmount all of them and for all of them :
linux>nandtest -m /dev/mtdx
Usually this doesn't add any new badblocks on top of what I get on nand
erase in uboot,
but I really haven't tested that much device to say.
After this procedure the NAND flash seems to work fine.
Do you think this is reliable way?
Is there something better I can do?
Has anyone got NAND component batch having more bad blocks then datasheet
allows.
Should we consider the provider unreliable?
Thank you
Dimitar
^ permalink raw reply [flat|nested] 6+ messages in thread
* [U-Boot] NAND flash - bad blocks
2013-01-10 7:56 [U-Boot] NAND flash - bad blocks Dimitar Penev
@ 2013-01-10 19:19 ` Scott Wood
2013-01-11 8:46 ` Dimitar Penev
0 siblings, 1 reply; 6+ messages in thread
From: Scott Wood @ 2013-01-10 19:19 UTC (permalink / raw)
To: u-boot
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?
After making sure that there's nothing wrong with your NAND driver or
controller that causes the OOB to be read incorrectly. Did you do
anything to the NAND chip prior to this "first erase"? In particular,
did you write to the OOB?
> 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.
> In Linux we have few mtd partitions on this NAND chip.
> Unmount all of them and for all of them :
> linux>nandtest -m /dev/mtdx
> Usually this doesn't add any new badblocks on top of what I get on
> nand erase in uboot,
> but I really haven't tested that much device to say.
>
> After this procedure the NAND flash seems to work fine.
> Do you think this is reliable way?
No.
-Scott
^ permalink raw reply [flat|nested] 6+ messages in thread
* [U-Boot] NAND flash - bad blocks
2013-01-10 19:19 ` Scott Wood
@ 2013-01-11 8:46 ` Dimitar Penev
2013-01-11 20:21 ` Scott Wood
0 siblings, 1 reply; 6+ messages in thread
From: Dimitar Penev @ 2013-01-11 8:46 UTC (permalink / raw)
To: u-boot
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.
>Did you do anything to the NAND chip prior to this "first erase"? In
>particular, did you write to the OOB?
For boards coming out of the assembly house:
I load uboot in SPI flash, boot from SPI and get the NAND chip recognized
properly.
On 'nand erase.chip' command I get bunch of bad blocks.
So I guess we haven't even touched OOB before 'nand erase'
Assuming the components are OK the only possible explanation could be
overheating
of the chips in the assembly house. Does anybody get something similar?
>
>> 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.
>
>> In Linux we have few mtd partitions on this NAND chip.
>> Unmount all of them and for all of them :
>> linux>nandtest -m /dev/mtdx
>> Usually this doesn't add any new badblocks on top of what I get on nand
>> erase in uboot,
>> but I really haven't tested that much device to say.
>>
>> After this procedure the NAND flash seems to work fine.
>> Do you think this is reliable way?
>
>No.
Thanks Scott.
Is there any procedure to analyze the nand flash for bad blocks?
>
>-Scott
Best Regards
Dimitar
^ permalink raw reply [flat|nested] 6+ messages in thread
* [U-Boot] NAND flash - bad blocks
2013-01-11 8:46 ` Dimitar Penev
@ 2013-01-11 20:21 ` Scott Wood
2013-01-15 11:09 ` Dimitar Penev
0 siblings, 1 reply; 6+ messages in thread
From: Scott Wood @ 2013-01-11 20:21 UTC (permalink / raw)
To: u-boot
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
^ permalink raw reply [flat|nested] 6+ messages in thread
* [U-Boot] NAND flash - bad blocks
2013-01-11 20:21 ` Scott Wood
@ 2013-01-15 11:09 ` Dimitar Penev
2013-01-15 17:33 ` Scott Wood
0 siblings, 1 reply; 6+ messages in thread
From: Dimitar Penev @ 2013-01-15 11:09 UTC (permalink / raw)
To: u-boot
Hi Scott,
I have tried to do some more tests on the board with the NAND chip I have
scrub-ed
-I have done 'nand erase.chip clean' and tried to probe different nand
regions
(I have 128MB RAM and 1GB NAND and I am not sure how I could dump the whole
NAND at once)
It seems the whole NAND is 0xFF
After that I have written 10MB at the beginning of the NAND and those data
was verified to be written OK
Outside of the 10MB region the NAND stays 0xFF
in Linux 'nandtest' doesn't report any issue.
So I tend to think that nand scrub did a good think for me.
Best Regards
Dimitar
----- Original Message -----
From: "Scott Wood" <scottwood@freescale.com>
To: "Dimitar Penev" <dpn@switchfin.org>
Cc: <u-boot@lists.denx.de>
Sent: Friday, January 11, 2013 10:21 PM
Subject: Re: [U-Boot] NAND flash - bad blocks
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
^ permalink raw reply [flat|nested] 6+ messages in thread
* [U-Boot] NAND flash - bad blocks
2013-01-15 11:09 ` Dimitar Penev
@ 2013-01-15 17:33 ` Scott Wood
0 siblings, 0 replies; 6+ messages in thread
From: Scott Wood @ 2013-01-15 17:33 UTC (permalink / raw)
To: u-boot
On 01/15/2013 05:09:16 AM, Dimitar Penev wrote:
> Hi Scott,
>
> I have tried to do some more tests on the board with the NAND chip I
> have scrub-ed
>
> -I have done 'nand erase.chip clean'
Don't specify "clean". That will cause jffs2 cleanmarkers to be
written. Not all NAND chips can handle partial programming, and in any
case it's an unnecessary variable for figuring out the bad block
situation.
> and tried to probe different nand regions
> (I have 128MB RAM and 1GB NAND and I am not sure how I could dump the
> whole NAND at once)
> It seems the whole NAND is 0xFF
Including OOB?
> So I tend to think that nand scrub did a good think for me.
No, it didn't. You are ignoring the problem.
-Scott
^ permalink raw reply [flat|nested] 6+ messages in thread
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2013-01-10 7:56 [U-Boot] NAND flash - bad blocks Dimitar Penev
2013-01-10 19:19 ` Scott Wood
2013-01-11 8:46 ` Dimitar Penev
2013-01-11 20:21 ` Scott Wood
2013-01-15 11:09 ` Dimitar Penev
2013-01-15 17:33 ` Scott Wood
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