[U-Boot-Users] Problem in writing downloaded image to NAND device

[Dharmosoth Seetharam]

Hi, 

I have gone thorugh the nand write code in u-boot.
But, i didn't get any problem in that.

Does it work for you guys (ie.writing to NAND device) 
?? Or Problem with my NAND device itself ??

NAND devie : Samsung, 256 MB. 

Any one tried the following command ???

>>nand write 0x22200000 0x0 0x800 (???)
>>md 0x22200000 (??)

Thanks,
Seetharam









--- Stefan Roese <sr at denx.de> wrote:

> On Wednesday 28 November 2007, Dharmosoth Seetharam
> wrote:
> > I have one doubt in NAND write/read PATH.
> >
> > > >  nand_write() --> nand_write_ecc() -->
> > > >  nand_write_page() --> nand_write_buf() -->
> > > >
> > > >
> > > >  in nand_write_buf() :
> > > >
> > > >  for (i=0; i<len; i++) {
> > > >       writeb(buf[i], this->IO_ADDR_W);
> > > >
> > > > << writeb is defined as
> > > >    (*(volatile unsigned char *)(a) = (v)) >>
> >
> > How can be "n" (where n=len) characters are
> > going to written this->IO_ADDR_W.
> >
> >
> > As per the above fro loop, I am getting confuse
> > that is - for each character from buf ( ie.
> buf[i])
> > the dest. address will be the same. So, there will
> be
> > a overwriting to the same dest. address in NAND.
> >
> > Is there any logic behind this stmt ??
> 
> Yes. This is the way is supposed to work. NAND FLASH
> chips don't have a "flat 
> address" model like NOR chips do. They don't have
> address signals at all. You 
> have to write the address using the data signals
> before writing the data 
> itself. This is done in conjunction with some
> control signals. So the data 
> signals are in reality multiplexed address/data
> pins.
> 
> > Please suggest me the right way to understand the
> > NAND write PATH from U-Boot code.
> 
> I suggest you take a look at a NAND chip data sheet
> to understand how NAND 
> chips are used.
> 
> Best regards,
> Stefan
> 
>
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