How common is OTP support in NAND flash?

How common is OTP support in NAND flash?

[Subodh Nijsure]

I see that MTD char drivers have support for programming the OTP pages 
on NAND flash, some questions regarding that.

Do most flash chip vendors support on-flash OTP pages or if one develops 
product that depends on using data from flash OTP, one would be locked 
into that specific vendors.

And does anybody know if these OTP pages are also subjected to 
bit-flipping or one shouldn't have to worry about that for OTP pages?

-Subodh

Re: How common is OTP support in NAND flash?

[Artem Bityutskiy]

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On Sun, 2012-05-13 at 07:25 -0700, Subodh Nijsure wrote:
> I see that MTD char drivers have support for programming the OTP pages 
> on NAND flash, some questions regarding that.
> 
> Do most flash chip vendors support on-flash OTP pages or if one develops 
> product that depends on using data from flash OTP, one would be locked 
> into that specific vendors.
> 
> And does anybody know if these OTP pages are also subjected to 
> bit-flipping or one shouldn't have to worry about that for OTP pages?

I think this OTP stuff is ad-hoc and was not designed carefully. I
cannot tell for sure, but most probably this is very vendor/HW -
specific.

-- 
Best Regards,
Artem Bityutskiy

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Re: How common is OTP support in NAND flash?

[Ricard Wanderlof]

> On Sun, 2012-05-13 at 07:25 -0700, Subodh Nijsure wrote:
>> I see that MTD char drivers have support for programming the OTP pages
>> on NAND flash, some questions regarding that.
>>
>> Do most flash chip vendors support on-flash OTP pages or if one develops
>> product that depends on using data from flash OTP, one would be locked
>> into that specific vendors.
>>
>> And does anybody know if these OTP pages are also subjected to
>> bit-flipping or one shouldn't have to worry about that for OTP pages?

I actually can't say I know, but since it is OTP, it's not possible to 
erase and reprogram the data; and it's intended use for more or less 
permanent information would strongly suggest that it must be an array of 
classic EPROM cells with essentially no bit rot or it wouldn't be very 
useful.

/Ricard
-- 
Ricard Wolf Wanderlöf                           ricardw(at)axis.com
Axis Communications AB, Lund, Sweden            www.axis.com
Phone +46 46 272 2016                           Fax +46 46 13 61 30