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Date: Wed, 18 Jul 2018 23:23:50 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Abhishek Sahu <absahu@...eaurora.org>
Cc: Boris Brezillon <boris.brezillon@...tlin.com>,
David Woodhouse <dwmw2@...radead.org>,
Brian Norris <computersforpeace@...il.com>,
Marek Vasut <marek.vasut@...il.com>,
Richard Weinberger <richard@....at>,
linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-mtd@...ts.infradead.org, Andy Gross <andy.gross@...aro.org>
Subject: Re: [PATCH 2/5] mtd: rawnand: qcom: remove driver specific
block_markbad function
Boris,
Can you please check the change in qcom_nandc_write_oob() is
valid? I think it is but as this is a bit of a hack I prefer double checking.
Thanks,
Miquèl
Abhishek Sahu <absahu@...eaurora.org> wrote on Fri, 6 Jul 2018
13:21:56 +0530:
> The NAND base layer calls write_oob() by setting bytes at
> chip->badblockpos with value non 0xFF for updating bad block status.
> The QCOM NAND controller skips the bad block bytes while doing normal
> write with ECC enabled. When initial support for this driver was
> added, the driver specific function was added temporarily for
> block_markbad() with assumption to change for raw read in NAND base
> layer. Moving to raw read for block_markbad() seems to take more time
> so this patch removes driver specific block_markbad() function by
> using following HACK in write_oob() function.
>
> Check for BBM bytes in OOB and accordingly do raw write for updating
> BBM bytes in NAND flash or normal write for updating available OOB
> bytes.
>
> Signed-off-by: Abhishek Sahu <absahu@...eaurora.org>
> ---
> drivers/mtd/nand/raw/qcom_nandc.c | 103 +++++++++++++++-----------------------
> 1 file changed, 40 insertions(+), 63 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
> index ea253ac..df12cf3 100644
> --- a/drivers/mtd/nand/raw/qcom_nandc.c
> +++ b/drivers/mtd/nand/raw/qcom_nandc.c
> @@ -2138,28 +2138,57 @@ static int qcom_nandc_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
> 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;
> - u8 *oob = chip->oob_poi;
> - int data_size, oob_size;
> + u8 *oob = chip->oob_poi, bbm_byte;
> + int data_size, oob_size, bbm_offset, write_size;
> int ret;
>
> - host->use_ecc = true;
> clear_bam_transaction(nandc);
>
> - /* calculate the data and oob size for the last codeword/step */
> - data_size = ecc->size - ((ecc->steps - 1) << 2);
> - oob_size = mtd->oobavail;
> + /*
> + * The NAND base layer calls ecc->write_oob() by setting bytes at
> + * chip->badblockpos (chip->badblockpos will be 0 for QCOM NAND
> + * controller layout) in OOB buffer with value other that 0xFF
> + * for updating bad block status. QCOM NAND controller skips
> + * BBM bytes while writing with ECC, so following HACK has been
> + * added in this function for using generic block_markbad() function.
> + *
> + * Check for BBM bytes in OOB and accordingly do raw write for
> + * updating BBM bytes in NAND flash or normal write with ECC for
> + * updating available OOB bytes.
> + */
> + bbm_byte = oob[0];
> + if (chip->options & NAND_BUSWIDTH_16)
> + bbm_byte &= oob[1];
>
> - memset(nandc->data_buffer, 0xff, host->cw_data);
> - /* override new oob content to last codeword */
> - mtd_ooblayout_get_databytes(mtd, nandc->data_buffer + data_size, oob,
> - 0, mtd->oobavail);
> + /* Write BBM bytes by doing raw write. */
> + if (bbm_byte != 0xff) {
> + host->use_ecc = false;
> + memset(nandc->data_buffer, 0xff, host->cw_size);
> + /* Determine the BBM bytes position and update the same */
> + bbm_offset = mtd->writesize - host->cw_size * (ecc->steps - 1);
> + memcpy(nandc->data_buffer + bbm_offset, oob, host->bbm_size);
> + write_size = host->cw_size;
> + /* Write OOB bytes by doing normal write with ECC */
> + } else {
> + host->use_ecc = true;
> + /* calculate the data and oob size for the last codeword/step */
> + data_size = ecc->size - ((ecc->steps - 1) << 2);
> + oob_size = mtd->oobavail;
> +
> + memset(nandc->data_buffer, 0xff, host->cw_data);
> + /* override new oob content to last codeword */
> + mtd_ooblayout_get_databytes(mtd, nandc->data_buffer + data_size,
> + oob, 0, mtd->oobavail);
> +
> + write_size = data_size + oob_size;
> + }
>
> set_address(host, host->cw_size * (ecc->steps - 1), page);
> update_rw_regs(host, 1, false);
>
> config_nand_page_write(nandc);
> write_data_dma(nandc, FLASH_BUF_ACC,
> - nandc->data_buffer, data_size + oob_size, 0);
> + nandc->data_buffer, write_size, 0);
> config_nand_cw_write(nandc);
>
> ret = submit_descs(nandc);
> @@ -2174,48 +2203,6 @@ static int qcom_nandc_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
> return nand_prog_page_end_op(chip);
> }
>
> -static int qcom_nandc_block_markbad(struct mtd_info *mtd, loff_t ofs)
> -{
> - struct nand_chip *chip = mtd_to_nand(mtd);
> - 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 page, ret;
> -
> - clear_read_regs(nandc);
> - clear_bam_transaction(nandc);
> -
> - /*
> - * to mark the BBM as bad, we flash the entire last codeword with 0s.
> - * we don't care about the rest of the content in the codeword since
> - * we aren't going to use this block again
> - */
> - memset(nandc->data_buffer, 0x00, host->cw_size);
> -
> - page = (int)(ofs >> chip->page_shift) & chip->pagemask;
> -
> - /* prepare write */
> - host->use_ecc = false;
> - set_address(host, host->cw_size * (ecc->steps - 1), page);
> - update_rw_regs(host, 1, false);
> -
> - config_nand_page_write(nandc);
> - write_data_dma(nandc, FLASH_BUF_ACC,
> - nandc->data_buffer, host->cw_size, 0);
> - config_nand_cw_write(nandc);
> -
> - ret = submit_descs(nandc);
> -
> - free_descs(nandc);
> -
> - if (ret) {
> - dev_err(nandc->dev, "failure to update BBM\n");
> - return -EIO;
> - }
> -
> - return nand_prog_page_end_op(chip);
> -}
> -
> /*
> * the three functions below implement chip->read_byte(), chip->read_buf()
> * and chip->write_buf() respectively. these aren't used for
> @@ -2757,16 +2744,6 @@ static int qcom_nand_host_init(struct qcom_nand_controller *nandc,
> chip->set_features = nand_get_set_features_notsupp;
> chip->get_features = nand_get_set_features_notsupp;
>
> - /*
> - * the bad block marker is writable only when we write the last codeword
> - * of a page with ECC disabled. currently, the nand_base and nand_bbt
> - * helpers don't allow us to write BB from a nand chip with ECC
> - * disabled (MTD_OPS_PLACE_OOB is set by default). use the block_markbad
> - * helpers until we permanently switch to using
> - * MTD_OPS_RAW for all drivers (with the help of badblockbits)
> - */
> - chip->block_markbad = qcom_nandc_block_markbad;
> -
> chip->controller = &nandc->controller;
> chip->options |= NAND_NO_SUBPAGE_WRITE | NAND_USE_BOUNCE_BUFFER |
> NAND_SKIP_BBTSCAN;
--
Miquel Raynal, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
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