Reading less than page size from NAND ok?

Reading less than page size from NAND ok?

[Ricard Wanderlof]

In the NAND boot code for U-Boot 1.4.4 (which use MTD (albeit an old 
version)), there is a note that when reading from NAND flash via the mtd 
layer (i.e. eventually ending up in nand_do_read_ecc()), one should start 
reading on a page boundary and read at least one page of data, in order to 
get proper ECC behavior.

However, when looking at the latest mtd code, it appears that this no 
longer is the case - when reading bursts of data less than one page, the 
data is internally buffered and a complete page read so that ECC is always 
applied properly. Is this in fact the case, or have I missed something 
vital here? (Was there such a limitation once?)

/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

Re: Reading less than page size from NAND ok?

[Artem Bityutskiy]

On Wed, 2006-10-18 at 13:22 +0200, Ricard Wanderlof wrote:
> In the NAND boot code for U-Boot 1.4.4 (which use MTD (albeit an old 
> version)), there is a note that when reading from NAND flash via the mtd 
> layer (i.e. eventually ending up in nand_do_read_ecc()), one should start 
> reading on a page boundary and read at least one page of data, in order to 
> get proper ECC behavior.
> 
> However, when looking at the latest mtd code, it appears that this no 
> longer is the case - when reading bursts of data less than one page, the 
> data is internally buffered and a complete page read so that ECC is always 
> applied properly. Is this in fact the case, or have I missed something 
> vital here? (Was there such a limitation once?)
> 

I am not sure about the past, but now you can read from any offset and
any number of bytes using MTD interface, even though you read from NAND
flash which has minimal I/O unit = 1 NAND page. MTD takes care of this.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)