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

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