[U-Boot] flash post test

[U-Boot] flash post test

[vk]

Hi all,


Currently I am testing the Flash memory by using "Write and Read the
same pattern" method (Protecting the UBoot Flash Sectors).

Is it safer to test flash memory during bootup?what if power gets off during
process?

I want to know whether there is any alternative method to test the
complete FLASH MEMORY.

[U-Boot] flash post test

[Albert ARIBAUD]

Hi vk,

Le 31/01/2012 10:27, vk a ?crit :
> Hi all,
>
>
> Currently I am testing the Flash memory by using "Write and Read the
> same pattern" method (Protecting the UBoot Flash Sectors).
>
> Is it safer to test flash memory during bootup?what if power gets off during
> process?
>
> I want to know whether there is any alternative method to test the
> complete FLASH MEMORY.

Do you mean that you want to test the flash by writing to it on every 
power-up? What is the point?

Amicalement,
-- 
Albert.

[U-Boot] flash post test

[vaibhav kothari]

hi albert

Yes,actually there is already support of flash test in POST of latest
uboot.They are testing flash on every power on so am I for my board.But i
don't want to disturb sectors in which uboot code relies. Can you help me
here?
On Sat, Feb 4, 2012 at 3:02 AM, Albert ARIBAUD <albert.u.boot@aribaud.net>wrote:

> Hi vk,
>
> Le 31/01/2012 10:27, vk a ?crit :
>
>  Hi all,
>>
>>
>> Currently I am testing the Flash memory by using "Write and Read the
>> same pattern" method (Protecting the UBoot Flash Sectors).
>>
>> Is it safer to test flash memory during bootup?what if power gets off
>> during
>> process?
>>
>> I want to know whether there is any alternative method to test the
>> complete FLASH MEMORY.
>>
>
> Do you mean that you want to test the flash by writing to it on every
> power-up? What is the point?
>
> Amicalement,
> --
> Albert.
>

[U-Boot] flash post test

[Albert ARIBAUD]

Hi Vaibhav,

Le 06/02/2012 05:57, vaibhav kothari a ?crit :
> hi albert
>
> Yes,actually there is already support of flash test in POST of latest
> uboot.They are testing flash on every power on so am I for my board.But i
> don't want to disturb sectors in which uboot code relies. Can you help me
> here?

I am no NAND specialist, but I do hope NAND POST tests are pure read 
tests and thus are not affected by poweroffs (and can actually test any 
part of NAND).

Amicalement,
-- 
Albert.

[U-Boot] flash post test

[Scott Wood]

On 02/06/2012 04:23 PM, Albert ARIBAUD wrote:
> Hi Vaibhav,
> 
> Le 06/02/2012 05:57, vaibhav kothari a ?crit :
>> hi albert
>>
>> Yes,actually there is already support of flash test in POST of latest
>> uboot.They are testing flash on every power on so am I for my board.But i
>> don't want to disturb sectors in which uboot code relies. Can you help me
>> here?
> 
> I am no NAND specialist, but I do hope NAND POST tests are pure read
> tests and thus are not affected by poweroffs (and can actually test any
> part of NAND).

NAND has a property called "read disturb", where excessively reading a
sector without writing to it can eventually cause data loss.  U-Boot is
already read once per boot, but reading it a second time could halve the
expected lifetime.  Data managed by something like ubi is be scrubbed in
a way that avoids this, but U-Boot itself is not usually managed in this
way (boot hardware/rom does not understand ubi).

-Scott

[U-Boot] flash post test

[Albert ARIBAUD]

Hi Scott,

Le 06/02/2012 23:55, Scott Wood a ?crit :
> On 02/06/2012 04:23 PM, Albert ARIBAUD wrote:
>> Hi Vaibhav,
>>
>> Le 06/02/2012 05:57, vaibhav kothari a ?crit :
>>> hi albert
>>>
>>> Yes,actually there is already support of flash test in POST of latest
>>> uboot.They are testing flash on every power on so am I for my board.But i
>>> don't want to disturb sectors in which uboot code relies. Can you help me
>>> here?
>>
>> I am no NAND specialist, but I do hope NAND POST tests are pure read
>> tests and thus are not affected by poweroffs (and can actually test any
>> part of NAND).
>
> NAND has a property called "read disturb", where excessively reading a
> sector without writing to it can eventually cause data loss.  U-Boot is
> already read once per boot, but reading it a second time could halve the
> expected lifetime.  Data managed by something like ubi is be scrubbed in
> a way that avoids this, but U-Boot itself is not usually managed in this
> way (boot hardware/rom does not understand ubi).

I *did* say I am not a NAND expert. :)

Thanks Scott. But then, isn't NAND testing a kind of catch-22, where by 
actually tesing if NAND works it one ends up weakening it either through 
read disturb, or simply through writes?

> -Scott

Amicalement,
-- 
Albert.

[U-Boot] flash post test

[Scott Wood]

On 02/06/2012 04:59 PM, Albert ARIBAUD wrote:
> Hi Scott,
> 
> Le 06/02/2012 23:55, Scott Wood a ?crit :
>> On 02/06/2012 04:23 PM, Albert ARIBAUD wrote:
>>> Hi Vaibhav,
>>>
>>> Le 06/02/2012 05:57, vaibhav kothari a ?crit :
>>>> hi albert
>>>>
>>>> Yes,actually there is already support of flash test in POST of latest
>>>> uboot.They are testing flash on every power on so am I for my
>>>> board.But i
>>>> don't want to disturb sectors in which uboot code relies. Can you
>>>> help me
>>>> here?
>>>
>>> I am no NAND specialist, but I do hope NAND POST tests are pure read
>>> tests and thus are not affected by poweroffs (and can actually test any
>>> part of NAND).
>>
>> NAND has a property called "read disturb", where excessively reading a
>> sector without writing to it can eventually cause data loss.  U-Boot is
>> already read once per boot, but reading it a second time could halve the
>> expected lifetime.  Data managed by something like ubi is be scrubbed in
>> a way that avoids this, but U-Boot itself is not usually managed in this
>> way (boot hardware/rom does not understand ubi).
> 
> I *did* say I am not a NAND expert. :)
> 
> Thanks Scott. But then, isn't NAND testing a kind of catch-22, where by
> actually tesing if NAND works it one ends up weakening it either through
> read disturb, or simply through writes?

It's fine for occasional manual testing, or routine testing of an area
that gets properly scrubbed.

-Scott

[U-Boot] flash post test

[vaibhav kothari]

hi albert,Scott

Thnks for your reply.Other than uib ,is there any data pattern/algorithm
for flash testing which effects less on lifespan of flash??