Hi Abhishek, On Thu, 12 Apr 2018 12:36:42 +0530, Abhishek Sahu <[email protected]> wrote:
> On 2018-04-10 15:14, Miquel Raynal wrote: > > Hi Abhishek, > > > On Wed, 4 Apr 2018 18:12:24 +0530, Abhishek Sahu > > <[email protected]> wrote: > > >> This patch does minor code reorganization for raw reads. > >> Currently the raw read is required for complete page but for > >> subsequent patches related with erased codeword bit flips > >> detection, only few CW should be read. So, this patch adds > >> helper function and introduces the read CW bitmask which > >> specifies which CW reads are required in complete page. > > > I am not sure this is the right approach for subpage reads. If the > > controller supports it, you should just enable it in chip->options. > > > Thanks Miquel. > > It is internal to this file only. This patch makes one static helper > function which provides the support to read subpages. Drivers should expose raw helpers, why keeping this helper static then? > > >> >> Signed-off-by: Abhishek Sahu <[email protected]> > >> --- > >> drivers/mtd/nand/qcom_nandc.c | 186 >> > >> +++++++++++++++++++++++++----------------- > >> 1 file changed, 110 insertions(+), 76 deletions(-) > >> >> diff --git a/drivers/mtd/nand/qcom_nandc.c >> > >> >> b/drivers/mtd/nand/qcom_nandc.c > >> index 40c790e..f5d1fa4 100644 > >> --- a/drivers/mtd/nand/qcom_nandc.c > >> +++ b/drivers/mtd/nand/qcom_nandc.c > >> @@ -1590,6 +1590,114 @@ static int check_flash_errors(struct >> > >> qcom_nand_host *host, int cw_cnt) > >> } > >> >> /* > >> + * Helper to perform the page raw read operation. The read_cw_mask >> > >> will be > >> + * used to specify the codewords for which the data should be read. >> The > >> + * single page contains multiple CW. Sometime, only few CW data is >> > >> required > >> + * in complete page. Also, start address will be determined with > >> + * this CW mask to skip unnecessary data copy from NAND flash device. >> > >> Then, > >> + * actual data copy from NAND controller to data buffer will be done >> > >> only > >> + * for the CWs which have the mask set. > >> + */ > >> +static int > >> +nandc_read_page_raw(struct mtd_info *mtd, struct nand_chip *chip, > >> + u8 *data_buf, u8 *oob_buf, > >> + int page, unsigned long read_cw_mask) > >> +{ > >> + struct qcom_nand_host *host = to_qcom_nand_host(chip); > >> + struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip); > >> + struct nand_ecc_ctrl *ecc = &chip->ecc; > >> + int i, ret; > >> + int read_loc, start_step, last_step; > >> + > >> + nand_read_page_op(chip, page, 0, NULL, 0); > >> + > >> + host->use_ecc = false; > >> + start_step = ffs(read_cw_mask) - 1; > >> + last_step = fls(read_cw_mask); > >> + > >> + clear_bam_transaction(nandc); > >> + set_address(host, host->cw_size * start_step, page); > >> + update_rw_regs(host, last_step - start_step, true); > >> + config_nand_page_read(nandc); > >> + > >> + for (i = start_step; i < last_step; i++) { > >> + int data_size1, data_size2, oob_size1, oob_size2; > >> + int reg_off = FLASH_BUF_ACC; > >> + > >> + data_size1 = mtd->writesize - host->cw_size * (ecc->steps - 1); > >> + oob_size1 = host->bbm_size; > >> + > >> + if (i == (ecc->steps - 1)) { > >> + data_size2 = ecc->size - data_size1 - > >> + ((ecc->steps - 1) << 2); > >> + oob_size2 = (ecc->steps << 2) + host->ecc_bytes_hw + > >> + host->spare_bytes; > >> + } else { > >> + data_size2 = host->cw_data - data_size1; > >> + oob_size2 = host->ecc_bytes_hw + host->spare_bytes; > >> + } > >> + > >> + /* > >> + * Don't perform actual data copy from NAND controller to data > >> + * buffer through DMA for this codeword > >> + */ > >> + if (!(read_cw_mask & BIT(i))) { > >> + if (nandc->props->is_bam) > >> + nandc_set_read_loc(nandc, 0, 0, 0, 1); > >> + > >> + config_nand_cw_read(nandc, false); > >> + > >> + data_buf += data_size1 + data_size2; > >> + oob_buf += oob_size1 + oob_size2; > >> + > >> + continue; > >> + } > >> + > >> + if (nandc->props->is_bam) { > >> + read_loc = 0; > >> + nandc_set_read_loc(nandc, 0, read_loc, data_size1, 0); > >> + read_loc += data_size1; > >> + > >> + nandc_set_read_loc(nandc, 1, read_loc, oob_size1, 0); > >> + read_loc += oob_size1; > >> + > >> + nandc_set_read_loc(nandc, 2, read_loc, data_size2, 0); > >> + read_loc += data_size2; > >> + > >> + nandc_set_read_loc(nandc, 3, read_loc, oob_size2, 1); > >> + } > >> + > >> + config_nand_cw_read(nandc, false); > >> + > >> + read_data_dma(nandc, reg_off, data_buf, data_size1, 0); > >> + reg_off += data_size1; > >> + data_buf += data_size1; > >> + > >> + read_data_dma(nandc, reg_off, oob_buf, oob_size1, 0); > >> + reg_off += oob_size1; > >> + oob_buf += oob_size1; > >> + > >> + read_data_dma(nandc, reg_off, data_buf, data_size2, 0); > >> + reg_off += data_size2; > >> + data_buf += data_size2; > >> + > >> + read_data_dma(nandc, reg_off, oob_buf, oob_size2, 0); > >> + oob_buf += oob_size2; > >> + } > >> + > >> + ret = submit_descs(nandc); > >> + if (ret) > >> + dev_err(nandc->dev, "failure to read raw page\n"); > >> + > >> + free_descs(nandc); > >> + > >> + if (!ret) > >> + ret = check_flash_errors(host, last_step - start_step); > >> + > >> + return 0; > >> +} > >> + > >> +/* > >> * reads back status registers set by the controller to notify page >> > >> read > >> * errors. this is equivalent to what 'ecc->correct()' would do. > >> */ > >> @@ -1839,82 +1947,8 @@ static int qcom_nandc_read_page_raw(struct >> > >> mtd_info *mtd, > >> struct nand_chip *chip, uint8_t *buf, > >> int oob_required, int page) > >> { > >> - struct qcom_nand_host *host = to_qcom_nand_host(chip); > >> - struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip); > >> - u8 *data_buf, *oob_buf; > >> - struct nand_ecc_ctrl *ecc = &chip->ecc; > >> - int i, ret; > >> - int read_loc; > >> - > >> - nand_read_page_op(chip, page, 0, NULL, 0); > >> - data_buf = buf; > >> - oob_buf = chip->oob_poi; > >> - > >> - host->use_ecc = false; > >> - > >> - clear_bam_transaction(nandc); > >> - update_rw_regs(host, ecc->steps, true); > >> - config_nand_page_read(nandc); > >> - > >> - for (i = 0; i < ecc->steps; i++) { > >> - int data_size1, data_size2, oob_size1, oob_size2; > >> - int reg_off = FLASH_BUF_ACC; > >> - > >> - data_size1 = mtd->writesize - host->cw_size * (ecc->steps - 1); > >> - oob_size1 = host->bbm_size; > >> - > >> - if (i == (ecc->steps - 1)) { > >> - data_size2 = ecc->size - data_size1 - > >> - ((ecc->steps - 1) << 2); > >> - oob_size2 = (ecc->steps << 2) + host->ecc_bytes_hw + > >> - host->spare_bytes; > >> - } else { > >> - data_size2 = host->cw_data - data_size1; > >> - oob_size2 = host->ecc_bytes_hw + host->spare_bytes; > >> - } > >> - > >> - if (nandc->props->is_bam) { > >> - read_loc = 0; > >> - nandc_set_read_loc(nandc, 0, read_loc, data_size1, 0); > >> - read_loc += data_size1; > >> - > >> - nandc_set_read_loc(nandc, 1, read_loc, oob_size1, 0); > >> - read_loc += oob_size1; > >> - > >> - nandc_set_read_loc(nandc, 2, read_loc, data_size2, 0); > >> - read_loc += data_size2; > >> - > >> - nandc_set_read_loc(nandc, 3, read_loc, oob_size2, 1); > >> - } > >> - > >> - config_nand_cw_read(nandc, false); > >> - > >> - read_data_dma(nandc, reg_off, data_buf, data_size1, 0); > >> - reg_off += data_size1; > >> - data_buf += data_size1; > >> - > >> - read_data_dma(nandc, reg_off, oob_buf, oob_size1, 0); > >> - reg_off += oob_size1; > >> - oob_buf += oob_size1; > >> - > >> - read_data_dma(nandc, reg_off, data_buf, data_size2, 0); > >> - reg_off += data_size2; > >> - data_buf += data_size2; > >> - > >> - read_data_dma(nandc, reg_off, oob_buf, oob_size2, 0); > >> - oob_buf += oob_size2; > >> - } > >> - > >> - ret = submit_descs(nandc); > >> - if (ret) > >> - dev_err(nandc->dev, "failure to read raw page\n"); > >> - > >> - free_descs(nandc); > >> - > >> - if (!ret) > >> - ret = check_flash_errors(host, ecc->steps); > >> - > >> - return 0; > >> + return nandc_read_page_raw(mtd, chip, buf, chip->oob_poi, page, > >> + BIT(chip->ecc.steps) - 1); > > > I don't understand this. chip->ecc.steps is constant, right? So you > > always ask for the same subpage? > > We need to do raw read for subpages in which we got uncorrectable > error in next patch for erased page bitflip detection. This patch does > reorganization of raw read and moves common code in helper function > nandc_read_page_raw. > > For nomral raw read, all the subpages will be read so > BIT(chip->ecc.steps) - 1 is used for qcom_nandc_read_page_raw. > > While for erased page raw read, only those sub pages will be > read for which the controller gives the uncorrectable error. Still not okay: the driver should expose a way to do raw reads no matter the length and the start and you should use that in a generic way. > > Thanks, > Abhishek > > > >> } > >> >> /* implements ecc->read_oob() */ -- Miquel Raynal, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com
