[U-Boot] [PATCH 2/2] MTD:NAND: ADD new ECC mode NAND_ECC_HW_OOB_FIRST

[Scott Wood <scottwood@freescale.com>]

John Rigby wrote:
> Sorry for the late comments.  We have been trying to use this code with 
> the associated davinci 4-bit ecc patches and have some questions (inline).
> 
>     .....
>     +       uint8_t *ecc_code = chip->buffers->ecccode;
>     +       uint32_t *eccpos = chip->ecc.layout->eccpos;
>     +       uint8_t *ecc_calc = chip->buffers->ecccalc;
>     +
>     +       /* Read the OOB area first */
>     +       chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
> 
>  
> What about chips that do not support the  NAND_CMD_READOOB?  Do I need 
> to provide my own read routine for that case?

cmdfunc is supposed to fix that up.  This is already the case with 
existing code.

>     +       chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
>     +       chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page);
>     +
>     +       for (i = 0; i < chip->ecc.total; i++)
>     +               ecc_code[i] = chip->oob_poi[eccpos[i]];
>     +
>     +       for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
>     +               int stat;
>     +
>     +               chip->ecc.hwctl(mtd, NAND_ECC_READ);
>     +               chip->read_buf(mtd, p, eccsize);
>     +               chip->ecc.calculate(mtd, p, &ecc_calc[i]);
> 
>  
> Here you calculate ecc then never use the result?

Hmm, that looks wrong, both here and in the davinci driver.  Are the two 
calls to nand_davinci_4bit_readecc reading different things?  Does the 
calculate function have any side effects beyond producing data that is 
never used?

-Scott