Hi, Please see the replies inline..
From: Scott Wood [mailto:scottwood@freescale.com]
On Mon, 2013-09-30 at 19:43 +0530, Pekon Gupta wrote: +Platform specific options +=========================
- CONFIG_NAND_OMAP_ECCSCHEME
- On OMAP platforms, this specifies NAND ECC scheme.
- 1 - HAM1_SW 1-bit Hamming code using software library
(for legacy devices only)- 2 - HAM1_HW 1-bit Hamming code using GPMC hardware engine
(for legacy devices only)- 3 - BCH4_SW 4-bit BCH code (unsupported)
- 4 - BCH4_HW 4-bit BCH code (unsupported)
- 5 - BCH8_SW 8-bit BCH code with
- ecc calculation using GPMC hardware engine,- error detection using software library.- requires CONFIG_BCH to enable software BCHlibrary
(For legacy device which do not have ELM h/wengine)
- 6 - BCH8_HW 8-bit BCH code with
- ecc calculation using GPMC hardware engine,- error detection using ELM hardware engine.You should document the symbols, not the numbers that happen to be assigned to them.
Sorry din't get you. This is based on your below feedback http://lists.denx.de/pipermail/u-boot/2013-September/162773.html
Example: "6 - BCH8_HW" means 8-bit BCH ECC scheme using h/w engine. It is this number is what user needs to specify in include/configs/*.h Any other internal symbol like "OMAP_ECC_BCH8_CODE_SW" should not be exposed to user, user-interface should remain constant. This is similar to DT binding approach used in linux. Internal symbols are not exposed to users.
+/**
- omap_select_ecc_scheme - configures driver for particular ecc-scheme
- @nand: NAND chip device structure
- @ecc_scheme: ecc scheme to configure
- @pagesize: number of main-area bytes per page of NAND device
- @oobsize: number of OOB/spare bytes per page of NAND device
- */
+static int omap_select_ecc_scheme(struct nand_chip *nand, int
ecc_scheme,
unsigned int pagesize, unsigned int oobsize) {s/int ecc_scheme/enum omap_ecc ecc_scheme/
If this is only the cosmetic change, may be I'll take it separately in another patch. Also 'omap_select_ecc_scheme()' has default statement in last, which gracefully handles all un-supported ecc-schemes.
[snip]
- /* check if NAND spare/OOB has enough bytes to accomodate
ecclayout */
- if ((ecclayout->eccbytes + BADBLOCK_MARKER_LENGTH) > oobsize)
{
printf("nand: error: insufficient OOB bytes. require=%d\n", (ecclayout->eccbytes +BADBLOCK_MARKER_LENGTH));
return -EINVAL;- }
Check this before you make any changes to the current ECC setup.
'ecclayout->eccbytes' depends on ECC scheme selected, therefore this check cannot be done before selecting ECC scheme first.
err = omap_select_ecc_scheme(nand,OMAP_ECC_HAM1_CODE_SW,
mtd->writesize, mtd->oobsize);- }
- if (err) {
printf("nand: error: could not switch ecc, reverting\n");omap_select_ecc_scheme(nand, bch->ecc_scheme,mtd->writesize, mtd->oobsize);return -EINVAL;You won't need to "revert" here if omap_select_ecc_scheme doesn't damage anything in error cases.
There are two cases when ECC selection could fail half-way: (1) when if(ecclayout->eccbytes + BADBLOCK > oobsize), as this check can only be done after selecting ECC scheme so it can fail
(2) if 'bch_priv.control = init_bch(13, 8, 0x201b);' fails. This check is also is done during ecc-scheme selection.
In both above cases, nand_chip.ecc information is half-configured so this reverting back to old ecc-scheme is essential.
with regards, pekon