Re: NAND flash

["Eric Bénard" <eric@eukrea.com>]

Hi,

On 21/03/2011 16:19, Vanalme Filip wrote:
> On our own i.MX27 based boards, we have Micron NAND flash memory
> (MT29F2G08ABBEAH4). Besides the BI-swapping problem for 2K NAND flashes, I can
> see that this chip needs an initial reset command before it becomes
> operational. This is something that has to be done in the early boot code, so
> before loading the first page of bootloader code (the reset should be sent
> before the first page of code can be read from flash).
>
>  From Freescale doc, I found that we have to blow certain fuses to make the
> i.MX27 boot from internal ROM. According to the document, the ROM code takes
> care about the initial reset before loading the first page of code from the
> NAND flash.
>
> I’m however a little concerned about this figure in the document :
>
> If I understand well, this should be the structure of the 2K NFC buffer when
> booting from internal ROM. I don’t think this will be the structure when
> loading the first page of Barebox code, correct ?
>
> Anyone familiar with this Micron specific flash problem ? And the consequences
> for Barebox ? Do we have to make modifications in the Barebox code to tackle
> this ?
>
> (because the Freescale document is rather WinCE related, I’m not sure this
> also applies to Barebox/Linux based systems…)
>
> I hope we didn’t make a bad choice of NAND flash in combination with i.MX27… ? ;-)
>
this may be the case as unless this has changed recently, flash requiring a 
reset command can't be used on i.MX27 for nand boot without extra logic as the 
internal bootrom doesn't send this reset command.

Eric

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