On 20/10/17 14:25, Boris Brezillon wrote:
> On Fri, 20 Oct 2017 12:59:31 +0300
> Roger Quadros <rogerq@xxxxxx> wrote:
>
>> Since v4.12, NAND subpage writes were causing a NULL pointer
>> dereference on OMAP platforms (omap2-nand) using OMAP_ECC_BCH4_CODE_HW,
>> OMAP_ECC_BCH8_CODE_HW and OMAP_ECC_BCH16_CODE_HW.
>>
>> This is because for those ECC modes, omap_calculate_ecc_bch()
>> generates ECC bytes for the entire (multi-sector) page and this can
>> overflow the ECC buffer provided by nand_write_subpage_hwecc()
>> as it expects ecc.calculate() to return ECC bytes for just one sector.
>>
>> However, the root cause of the problem is present much before
>> v4.12 but was not seen then as NAND buffers were being allocated
>> as one big chunck prior to
>> commit 3deb9979c731 ("mtd: nand: allocate aligned buffers if NAND_OWN_BUFFERS is unset")
>>
>> Fix the issue by providing a OMAP optimized write_subpage() implementation.
>>
>
> Fixes: xxxx ("yyyy")
>
> xxx being the commit that introduced the omap_calculate_ecc_bch() and
> assign chip->ecc.calculate to it.
>
>> cc: <stable@xxxxxxxxxxxxxxx> # v4.12+
>
> Shouldn't we try to backport the patch to pre-4.12 versions? I mean,
> the buffer overflow exist there as well, and we don't know what it
> corrupts exactly, but it's potentially harmful.
>
>> Signed-off-by: Roger Quadros <rogerq@xxxxxx>
>> ---
>> Changelog:
>> v2
>> - set ecc.calculate() to NULL for BCH4/8/16 with HW correction as in this
>> mode we don't support/need single sector ECC calculations to be used by NAND core.
>> - call omap_calculate_ecc_bch_multi() directly from omap_read/write_page_bch().
>>
>> drivers/mtd/nand/omap2.c | 338 +++++++++++++++++++++++++++++++----------------
>> 1 file changed, 225 insertions(+), 113 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
>> index 54540c8..a0bd456 100644
>> --- a/drivers/mtd/nand/omap2.c
>> +++ b/drivers/mtd/nand/omap2.c
>> @@ -1133,129 +1133,172 @@ static u8 bch8_polynomial[] = {0xef, 0x51, 0x2e, 0x09, 0xed, 0x93, 0x9a, 0xc2,
>> 0x97, 0x79, 0xe5, 0x24, 0xb5};
>>
>> /**
>> - * omap_calculate_ecc_bch - Generate bytes of ECC bytes
>> + * _omap_calculate_ecc_bch - Generate ECC bytes for one sector
>> * @mtd: MTD device structure
>> * @dat: The pointer to data on which ecc is computed
>> * @ecc_code: The ecc_code buffer
>> + * @i: The sector number (for a multi sector page)
>> *
>> - * Support calculating of BCH4/8 ecc vectors for the page
>> + * Support calculating of BCH4/8/16 ECC vectors for one sector
>> + * within a page. Sector number is in @i.
>> */
>> -static int __maybe_unused omap_calculate_ecc_bch(struct mtd_info *mtd,
>> - const u_char *dat, u_char *ecc_calc)
>> +static int _omap_calculate_ecc_bch(struct mtd_info *mtd,
>> + const u_char *dat, u_char *ecc_calc, int i)
>> {
>> struct omap_nand_info *info = mtd_to_omap(mtd);
>> int eccbytes = info->nand.ecc.bytes;
>> struct gpmc_nand_regs *gpmc_regs = &info->reg;
>> u8 *ecc_code;
>> - unsigned long nsectors, bch_val1, bch_val2, bch_val3, bch_val4;
>> + unsigned long bch_val1, bch_val2, bch_val3, bch_val4;
>> u32 val;
>> - int i, j;
>> + int j;
>> +
>> + ecc_code = ecc_calc;
>> + switch (info->ecc_opt) {
>> + case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
>> + case OMAP_ECC_BCH8_CODE_HW:
>> + bch_val1 = readl(gpmc_regs->gpmc_bch_result0[i]);
>> + bch_val2 = readl(gpmc_regs->gpmc_bch_result1[i]);
>> + bch_val3 = readl(gpmc_regs->gpmc_bch_result2[i]);
>> + bch_val4 = readl(gpmc_regs->gpmc_bch_result3[i]);
>> + *ecc_code++ = (bch_val4 & 0xFF);
>> + *ecc_code++ = ((bch_val3 >> 24) & 0xFF);
>> + *ecc_code++ = ((bch_val3 >> 16) & 0xFF);
>> + *ecc_code++ = ((bch_val3 >> 8) & 0xFF);
>> + *ecc_code++ = (bch_val3 & 0xFF);
>> + *ecc_code++ = ((bch_val2 >> 24) & 0xFF);
>> + *ecc_code++ = ((bch_val2 >> 16) & 0xFF);
>> + *ecc_code++ = ((bch_val2 >> 8) & 0xFF);
>> + *ecc_code++ = (bch_val2 & 0xFF);
>> + *ecc_code++ = ((bch_val1 >> 24) & 0xFF);
>> + *ecc_code++ = ((bch_val1 >> 16) & 0xFF);
>> + *ecc_code++ = ((bch_val1 >> 8) & 0xFF);
>> + *ecc_code++ = (bch_val1 & 0xFF);
>> + break;
>> + case OMAP_ECC_BCH4_CODE_HW_DETECTION_SW:
>> + case OMAP_ECC_BCH4_CODE_HW:
>> + bch_val1 = readl(gpmc_regs->gpmc_bch_result0[i]);
>> + bch_val2 = readl(gpmc_regs->gpmc_bch_result1[i]);
>> + *ecc_code++ = ((bch_val2 >> 12) & 0xFF);
>> + *ecc_code++ = ((bch_val2 >> 4) & 0xFF);
>> + *ecc_code++ = ((bch_val2 & 0xF) << 4) |
>> + ((bch_val1 >> 28) & 0xF);
>> + *ecc_code++ = ((bch_val1 >> 20) & 0xFF);
>> + *ecc_code++ = ((bch_val1 >> 12) & 0xFF);
>> + *ecc_code++ = ((bch_val1 >> 4) & 0xFF);
>> + *ecc_code++ = ((bch_val1 & 0xF) << 4);
>> + break;
>> + case OMAP_ECC_BCH16_CODE_HW:
>> + val = readl(gpmc_regs->gpmc_bch_result6[i]);
>> + ecc_code[0] = ((val >> 8) & 0xFF);
>> + ecc_code[1] = ((val >> 0) & 0xFF);
>> + val = readl(gpmc_regs->gpmc_bch_result5[i]);
>> + ecc_code[2] = ((val >> 24) & 0xFF);
>> + ecc_code[3] = ((val >> 16) & 0xFF);
>> + ecc_code[4] = ((val >> 8) & 0xFF);
>> + ecc_code[5] = ((val >> 0) & 0xFF);
>> + val = readl(gpmc_regs->gpmc_bch_result4[i]);
>> + ecc_code[6] = ((val >> 24) & 0xFF);
>> + ecc_code[7] = ((val >> 16) & 0xFF);
>> + ecc_code[8] = ((val >> 8) & 0xFF);
>> + ecc_code[9] = ((val >> 0) & 0xFF);
>> + val = readl(gpmc_regs->gpmc_bch_result3[i]);
>> + ecc_code[10] = ((val >> 24) & 0xFF);
>> + ecc_code[11] = ((val >> 16) & 0xFF);
>> + ecc_code[12] = ((val >> 8) & 0xFF);
>> + ecc_code[13] = ((val >> 0) & 0xFF);
>> + val = readl(gpmc_regs->gpmc_bch_result2[i]);
>> + ecc_code[14] = ((val >> 24) & 0xFF);
>> + ecc_code[15] = ((val >> 16) & 0xFF);
>> + ecc_code[16] = ((val >> 8) & 0xFF);
>> + ecc_code[17] = ((val >> 0) & 0xFF);
>> + val = readl(gpmc_regs->gpmc_bch_result1[i]);
>> + ecc_code[18] = ((val >> 24) & 0xFF);
>> + ecc_code[19] = ((val >> 16) & 0xFF);
>> + ecc_code[20] = ((val >> 8) & 0xFF);
>> + ecc_code[21] = ((val >> 0) & 0xFF);
>> + val = readl(gpmc_regs->gpmc_bch_result0[i]);
>> + ecc_code[22] = ((val >> 24) & 0xFF);
>> + ecc_code[23] = ((val >> 16) & 0xFF);
>> + ecc_code[24] = ((val >> 8) & 0xFF);
>> + ecc_code[25] = ((val >> 0) & 0xFF);
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + /* ECC scheme specific syndrome customizations */
>> + switch (info->ecc_opt) {
>> + case OMAP_ECC_BCH4_CODE_HW_DETECTION_SW:
>> + /* Add constant polynomial to remainder, so that
>> + * ECC of blank pages results in 0x0 on reading back
>> + */
>> + for (j = 0; j < eccbytes; j++)
>> + ecc_calc[j] ^= bch4_polynomial[j];
>> + break;
>> + case OMAP_ECC_BCH4_CODE_HW:
>> + /* Set 8th ECC byte as 0x0 for ROM compatibility */
>> + ecc_calc[eccbytes - 1] = 0x0;
>> + break;
>> + case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
>> + /* Add constant polynomial to remainder, so that
>> + * ECC of blank pages results in 0x0 on reading back
>> + */
>> + for (j = 0; j < eccbytes; j++)
>> + ecc_calc[j] ^= bch8_polynomial[j];
>> + break;
>> + case OMAP_ECC_BCH8_CODE_HW:
>> + /* Set 14th ECC byte as 0x0 for ROM compatibility */
>> + ecc_calc[eccbytes - 1] = 0x0;
>> + break;
>> + case OMAP_ECC_BCH16_CODE_HW:
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +/**
>> + * omap_calculate_ecc_bch_sw - ECC generator for sector for SW based correction
>> + * @mtd: MTD device structure
>> + * @dat: The pointer to data on which ecc is computed
>> + * @ecc_code: The ecc_code buffer
>> + *
>> + * Support calculating of BCH4/8/16 ECC vectors for one sector. This is used
>> + * when SW based correction is required as ECC is required for one sector
>> + * at a time.
>> + */
>> +static int omap_calculate_ecc_bch_sw(struct mtd_info *mtd,
>> + const u_char *dat, u_char *ecc_calc)
>> +{
>> + return _omap_calculate_ecc_bch(mtd, dat, ecc_calc, 0);
>> +}
>> +
>> +/**
>> + * omap_calculate_ecc_bch_multi - Generate ECC for multiple sectors
>> + * @mtd: MTD device structure
>> + * @dat: The pointer to data on which ecc is computed
>> + * @ecc_code: The ecc_code buffer
>> + *
>> + * Support calculating of BCH4/8/16 ecc vectors for the entire page in one go.
>> + */
>> +static int omap_calculate_ecc_bch_multi(struct mtd_info *mtd,
>> + const u_char *dat, u_char *ecc_calc)
>> +{
>> + struct omap_nand_info *info = mtd_to_omap(mtd);
>> + int eccbytes = info->nand.ecc.bytes;
>> + unsigned long nsectors;
>> + int i, ret;
>>
>> nsectors = ((readl(info->reg.gpmc_ecc_config) >> 4) & 0x7) + 1;
>> for (i = 0; i < nsectors; i++) {
>> - ecc_code = ecc_calc;
>> - switch (info->ecc_opt) {
>> - case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
>> - case OMAP_ECC_BCH8_CODE_HW:
>> - bch_val1 = readl(gpmc_regs->gpmc_bch_result0[i]);
>> - bch_val2 = readl(gpmc_regs->gpmc_bch_result1[i]);
>> - bch_val3 = readl(gpmc_regs->gpmc_bch_result2[i]);
>> - bch_val4 = readl(gpmc_regs->gpmc_bch_result3[i]);
>> - *ecc_code++ = (bch_val4 & 0xFF);
>> - *ecc_code++ = ((bch_val3 >> 24) & 0xFF);
>> - *ecc_code++ = ((bch_val3 >> 16) & 0xFF);
>> - *ecc_code++ = ((bch_val3 >> 8) & 0xFF);
>> - *ecc_code++ = (bch_val3 & 0xFF);
>> - *ecc_code++ = ((bch_val2 >> 24) & 0xFF);
>> - *ecc_code++ = ((bch_val2 >> 16) & 0xFF);
>> - *ecc_code++ = ((bch_val2 >> 8) & 0xFF);
>> - *ecc_code++ = (bch_val2 & 0xFF);
>> - *ecc_code++ = ((bch_val1 >> 24) & 0xFF);
>> - *ecc_code++ = ((bch_val1 >> 16) & 0xFF);
>> - *ecc_code++ = ((bch_val1 >> 8) & 0xFF);
>> - *ecc_code++ = (bch_val1 & 0xFF);
>> - break;
>> - case OMAP_ECC_BCH4_CODE_HW_DETECTION_SW:
>> - case OMAP_ECC_BCH4_CODE_HW:
>> - bch_val1 = readl(gpmc_regs->gpmc_bch_result0[i]);
>> - bch_val2 = readl(gpmc_regs->gpmc_bch_result1[i]);
>> - *ecc_code++ = ((bch_val2 >> 12) & 0xFF);
>> - *ecc_code++ = ((bch_val2 >> 4) & 0xFF);
>> - *ecc_code++ = ((bch_val2 & 0xF) << 4) |
>> - ((bch_val1 >> 28) & 0xF);
>> - *ecc_code++ = ((bch_val1 >> 20) & 0xFF);
>> - *ecc_code++ = ((bch_val1 >> 12) & 0xFF);
>> - *ecc_code++ = ((bch_val1 >> 4) & 0xFF);
>> - *ecc_code++ = ((bch_val1 & 0xF) << 4);
>> - break;
>> - case OMAP_ECC_BCH16_CODE_HW:
>> - val = readl(gpmc_regs->gpmc_bch_result6[i]);
>> - ecc_code[0] = ((val >> 8) & 0xFF);
>> - ecc_code[1] = ((val >> 0) & 0xFF);
>> - val = readl(gpmc_regs->gpmc_bch_result5[i]);
>> - ecc_code[2] = ((val >> 24) & 0xFF);
>> - ecc_code[3] = ((val >> 16) & 0xFF);
>> - ecc_code[4] = ((val >> 8) & 0xFF);
>> - ecc_code[5] = ((val >> 0) & 0xFF);
>> - val = readl(gpmc_regs->gpmc_bch_result4[i]);
>> - ecc_code[6] = ((val >> 24) & 0xFF);
>> - ecc_code[7] = ((val >> 16) & 0xFF);
>> - ecc_code[8] = ((val >> 8) & 0xFF);
>> - ecc_code[9] = ((val >> 0) & 0xFF);
>> - val = readl(gpmc_regs->gpmc_bch_result3[i]);
>> - ecc_code[10] = ((val >> 24) & 0xFF);
>> - ecc_code[11] = ((val >> 16) & 0xFF);
>> - ecc_code[12] = ((val >> 8) & 0xFF);
>> - ecc_code[13] = ((val >> 0) & 0xFF);
>> - val = readl(gpmc_regs->gpmc_bch_result2[i]);
>> - ecc_code[14] = ((val >> 24) & 0xFF);
>> - ecc_code[15] = ((val >> 16) & 0xFF);
>> - ecc_code[16] = ((val >> 8) & 0xFF);
>> - ecc_code[17] = ((val >> 0) & 0xFF);
>> - val = readl(gpmc_regs->gpmc_bch_result1[i]);
>> - ecc_code[18] = ((val >> 24) & 0xFF);
>> - ecc_code[19] = ((val >> 16) & 0xFF);
>> - ecc_code[20] = ((val >> 8) & 0xFF);
>> - ecc_code[21] = ((val >> 0) & 0xFF);
>> - val = readl(gpmc_regs->gpmc_bch_result0[i]);
>> - ecc_code[22] = ((val >> 24) & 0xFF);
>> - ecc_code[23] = ((val >> 16) & 0xFF);
>> - ecc_code[24] = ((val >> 8) & 0xFF);
>> - ecc_code[25] = ((val >> 0) & 0xFF);
>> - break;
>> - default:
>> - return -EINVAL;
>> - }
>> -
>> - /* ECC scheme specific syndrome customizations */
>> - switch (info->ecc_opt) {
>> - case OMAP_ECC_BCH4_CODE_HW_DETECTION_SW:
>> - /* Add constant polynomial to remainder, so that
>> - * ECC of blank pages results in 0x0 on reading back */
>> - for (j = 0; j < eccbytes; j++)
>> - ecc_calc[j] ^= bch4_polynomial[j];
>> - break;
>> - case OMAP_ECC_BCH4_CODE_HW:
>> - /* Set 8th ECC byte as 0x0 for ROM compatibility */
>> - ecc_calc[eccbytes - 1] = 0x0;
>> - break;
>> - case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
>> - /* Add constant polynomial to remainder, so that
>> - * ECC of blank pages results in 0x0 on reading back */
>> - for (j = 0; j < eccbytes; j++)
>> - ecc_calc[j] ^= bch8_polynomial[j];
>> - break;
>> - case OMAP_ECC_BCH8_CODE_HW:
>> - /* Set 14th ECC byte as 0x0 for ROM compatibility */
>> - ecc_calc[eccbytes - 1] = 0x0;
>> - break;
>> - case OMAP_ECC_BCH16_CODE_HW:
>> - break;
>> - default:
>> - return -EINVAL;
>> - }
>> + ret = _omap_calculate_ecc_bch(mtd, dat, ecc_calc, i);
>> + if (ret)
>> + return ret;
>>
>> - ecc_calc += eccbytes;
>> + ecc_calc += eccbytes;
>> }
>>
>> return 0;
>> @@ -1509,6 +1552,72 @@ static int omap_write_page_bch(struct mtd_info *mtd, struct nand_chip *chip,
>> }
>>
>> /**
>> + * omap_write_subpage_bch - BCH hardware ECC based subpage write
>> + * @mtd: mtd info structure
>> + * @chip: nand chip info structure
>> + * @offset: column address of subpage within the page
>> + * @data_len: data length
>> + * @buf: data buffer
>> + * @oob_required: must write chip->oob_poi to OOB
>> + * @page: page number to write
>> + *
>> + * OMAP optimized subpage write method.
>> + */
>> +static int omap_write_subpage_bch(struct mtd_info *mtd,
>> + struct nand_chip *chip, u32 offset,
>> + u32 data_len, const u8 *buf,
>> + int oob_required, int page)
>> +{
>> + u8 *ecc_calc = chip->buffers->ecccalc;
>> + int ecc_size = chip->ecc.size;
>> + int ecc_bytes = chip->ecc.bytes;
>> + int ecc_steps = chip->ecc.steps;
>> + u32 start_step = offset / ecc_size;
>> + u32 end_step = (offset + data_len - 1) / ecc_size;
>> + int step, ret = 0;
>> +
>> + /*
>> + * Write entire page at one go as it would be optimal
>> + * as ECC is calculated by hardware.
>> + * ECC is calculated for all subpages but we choose
>> + * only what we want.
>> + */
>> +
>> + /* Enable GPMC ECC engine */
>> + chip->ecc.hwctl(mtd, NAND_ECC_WRITE);
>> +
>> + /* Write data */
>> + chip->write_buf(mtd, buf, mtd->writesize);
>> +
>> + for (step = 0; step < ecc_steps; step++) {
>> + /* mask ECC of un-touched subpages by padding 0xFF */
>> + if (step < start_step || step > end_step)
>> + memset(ecc_calc, 0xff, ecc_bytes);
>> + else
>> + ret = _omap_calculate_ecc_bch(mtd, buf, ecc_calc, step);
>> +
>> + if (ret)
>> + return ret;
>> +
>> + buf += ecc_size;
>> + ecc_calc += ecc_bytes;
>> + }
>> +
>> + /* copy calculated ECC for whole page to chip->buffer->oob */
>> + /* this include masked-value(0xFF) for unwritten subpages */
>> + ecc_calc = chip->buffers->ecccalc;
>> + ret = mtd_ooblayout_set_eccbytes(mtd, ecc_calc, chip->oob_poi, 0,
>> + chip->ecc.total);
>> + if (ret)
>> + return ret;
>> +
>> + /* write OOB buffer to NAND device */
>> + chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);
>> +
>> + return 0;
>> +}
>> +
>> +/**
>> * omap_read_page_bch - BCH ecc based page read function for entire page
>> * @mtd: mtd info structure
>> * @chip: nand chip info structure
>> @@ -2044,7 +2153,7 @@ static int omap_nand_probe(struct platform_device *pdev)
>> nand_chip->ecc.strength = 4;
>> nand_chip->ecc.hwctl = omap_enable_hwecc_bch;
>> nand_chip->ecc.correct = nand_bch_correct_data;
>> - nand_chip->ecc.calculate = omap_calculate_ecc_bch;
>> + nand_chip->ecc.calculate = omap_calculate_ecc_bch_sw;
>> mtd_set_ooblayout(mtd, &omap_sw_ooblayout_ops);
>> /* Reserve one byte for the OMAP marker */
>> oobbytes_per_step = nand_chip->ecc.bytes + 1;
>> @@ -2066,9 +2175,10 @@ static int omap_nand_probe(struct platform_device *pdev)
>> nand_chip->ecc.strength = 4;
>> nand_chip->ecc.hwctl = omap_enable_hwecc_bch;
>> nand_chip->ecc.correct = omap_elm_correct_data;
>> - nand_chip->ecc.calculate = omap_calculate_ecc_bch;
>> + nand_chip->ecc.calculate = omap_calculate_ecc_bch_multi;
>
> It's still wrong. Didn't you say you would leave ecc->calculate
> unassigned in this case?
>
Ah, I forgot to commit :P. sorry.
>> nand_chip->ecc.read_page = omap_read_page_bch;
>> nand_chip->ecc.write_page = omap_write_page_bch;
>> + nand_chip->ecc.write_subpage = omap_write_subpage_bch;
>> mtd_set_ooblayout(mtd, &omap_ooblayout_ops);
>> oobbytes_per_step = nand_chip->ecc.bytes;
>>
>> @@ -2087,7 +2197,7 @@ static int omap_nand_probe(struct platform_device *pdev)
>> nand_chip->ecc.strength = 8;
>> nand_chip->ecc.hwctl = omap_enable_hwecc_bch;
>> nand_chip->ecc.correct = nand_bch_correct_data;
>> - nand_chip->ecc.calculate = omap_calculate_ecc_bch;
>> + nand_chip->ecc.calculate = omap_calculate_ecc_bch_sw;
>> mtd_set_ooblayout(mtd, &omap_sw_ooblayout_ops);
>> /* Reserve one byte for the OMAP marker */
>> oobbytes_per_step = nand_chip->ecc.bytes + 1;
>> @@ -2109,9 +2219,10 @@ static int omap_nand_probe(struct platform_device *pdev)
>> nand_chip->ecc.strength = 8;
>> nand_chip->ecc.hwctl = omap_enable_hwecc_bch;
>> nand_chip->ecc.correct = omap_elm_correct_data;
>> - nand_chip->ecc.calculate = omap_calculate_ecc_bch;
>> + nand_chip->ecc.calculate = omap_calculate_ecc_bch_multi;
>> nand_chip->ecc.read_page = omap_read_page_bch;
>> nand_chip->ecc.write_page = omap_write_page_bch;
>> + nand_chip->ecc.write_subpage = omap_write_subpage_bch;
>> mtd_set_ooblayout(mtd, &omap_ooblayout_ops);
>> oobbytes_per_step = nand_chip->ecc.bytes;
>>
>> @@ -2131,9 +2242,10 @@ static int omap_nand_probe(struct platform_device *pdev)
>> nand_chip->ecc.strength = 16;
>> nand_chip->ecc.hwctl = omap_enable_hwecc_bch;
>> nand_chip->ecc.correct = omap_elm_correct_data;
>> - nand_chip->ecc.calculate = omap_calculate_ecc_bch;
>> + nand_chip->ecc.calculate = omap_calculate_ecc_bch_multi;
>> nand_chip->ecc.read_page = omap_read_page_bch;
>> nand_chip->ecc.write_page = omap_write_page_bch;
>> + nand_chip->ecc.write_subpage = omap_write_subpage_bch;
>> mtd_set_ooblayout(mtd, &omap_ooblayout_ops);
>> oobbytes_per_step = nand_chip->ecc.bytes;
>>
>
--
cheers,
-roger
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