Re: [RFC] Change ECC algorithm from userspace

Javier Martinez Canillas
2011-10-28T12:00:53Z

On Fri, Oct 28, 2011 at 1:51 PM, Matthieu CASTET
<matthieu.castet@parrot.com> wrote:
> Javier Martinez Canillas a écrit :
>> On Fri, Oct 28, 2011 at 12:30 PM, Matthieu CASTET
>> <matthieu.castet@parrot.com> wrote:
>>> PS : note that some OMAP ROM support a better protection than Hamming (but the
>>> details are not public AFAIK)
>>>
>>> From OMAP34xx Multimedia Device, Silicon Revision 3.1.x, public version :
>>>
>>> Pages can contain errors caused by memory alteration. To correct these errors,
>>> the ROM code uses ECC,
>>> based on Hamming codes for SLC NAND and BCH (Bose, Ray-Chaudhuri, Hocquenghem)
>>> code for
>>> multilevel cell (MLC) devices. The computed ECC is compared to ECC stored in the
>>> spare area of the
>>> corresponding page. If there are uncorrectable errors, the ROM code returns with
>>> FAIL.
>>>
>>
>> Yes I've read that on the DM3730 TRM but as far as I understand only
>> applies to MLC devices, but ours is SLC.
>>
> It also works on SLC devices. We are using it on micron slc that need 4 bits ECC.
>

That is a great thing to know, I didn't get that from the
documentation (DM3730 TRM).

And this ECC scheme that is supported for SLC devices it is also BCH?
Or the ROM boot uses a different algorithm to calculate the codes to
be stored on the oob?

Thank and best regards,

--
Javier Martínez Canillas
(+34) 682 39 81 69
Barcelona, Spain