[PATCH v3] mtd: nand: brcmnand: fix mtd corrected bits stat
William Zhang
william.zhang at broadcom.com
Wed Jul 2 21:26:28 PDT 2025
On Wed, Jul 2, 2025 at 7:47 PM david regan <dregan at broadcom.com> wrote:
>
> From: David Regan <dregan at broadcom.com>
>
> Currently we attempt to get the amount of flipped bits from a hardware
> location which is reset on every subpage. Instead obtain total flipped
> bits stat from hardware accumulator. In addition identify the correct
> maximum subpage corrected bits.
>
> Signed-off-by: David Regan <dregan at broadcom.com>
> ---
> v3: Use brcmnand_corr_total to obtain maximum subpage flipped
> bits for further backwards compatibility.
>
> v2: Add >= v4 NAND controller support as requested by Jonas.
> mtd->ecc_stats.corrected accumulates instead of set to total.
> Remove DMA specific flipped bits count.
>
> ---
> drivers/mtd/nand/raw/brcmnand/brcmnand.c | 53 +++++++++++++++++-------
> 1 file changed, 38 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> index 62bdda3be92f..b13f5f8f0eec 100644
> --- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> @@ -359,6 +359,7 @@ enum brcmnand_reg {
> BRCMNAND_CORR_THRESHOLD_EXT,
> BRCMNAND_UNCORR_COUNT,
> BRCMNAND_CORR_COUNT,
> + BRCMNAND_READ_ERROR_COUNT,
> BRCMNAND_CORR_EXT_ADDR,
> BRCMNAND_CORR_ADDR,
> BRCMNAND_UNCORR_EXT_ADDR,
> @@ -389,6 +390,7 @@ static const u16 brcmnand_regs_v21[] = {
> [BRCMNAND_CORR_THRESHOLD_EXT] = 0,
> [BRCMNAND_UNCORR_COUNT] = 0,
> [BRCMNAND_CORR_COUNT] = 0,
> + [BRCMNAND_READ_ERROR_COUNT] = 0,
> [BRCMNAND_CORR_EXT_ADDR] = 0x60,
> [BRCMNAND_CORR_ADDR] = 0x64,
> [BRCMNAND_UNCORR_EXT_ADDR] = 0x68,
> @@ -419,6 +421,7 @@ static const u16 brcmnand_regs_v33[] = {
> [BRCMNAND_CORR_THRESHOLD_EXT] = 0,
> [BRCMNAND_UNCORR_COUNT] = 0,
> [BRCMNAND_CORR_COUNT] = 0,
> + [BRCMNAND_READ_ERROR_COUNT] = 0x80,
> [BRCMNAND_CORR_EXT_ADDR] = 0x70,
> [BRCMNAND_CORR_ADDR] = 0x74,
> [BRCMNAND_UNCORR_EXT_ADDR] = 0x78,
> @@ -449,6 +452,7 @@ static const u16 brcmnand_regs_v50[] = {
> [BRCMNAND_CORR_THRESHOLD_EXT] = 0,
> [BRCMNAND_UNCORR_COUNT] = 0,
> [BRCMNAND_CORR_COUNT] = 0,
> + [BRCMNAND_READ_ERROR_COUNT] = 0x80,
> [BRCMNAND_CORR_EXT_ADDR] = 0x70,
> [BRCMNAND_CORR_ADDR] = 0x74,
> [BRCMNAND_UNCORR_EXT_ADDR] = 0x78,
> @@ -479,6 +483,7 @@ static const u16 brcmnand_regs_v60[] = {
> [BRCMNAND_CORR_THRESHOLD_EXT] = 0xc4,
> [BRCMNAND_UNCORR_COUNT] = 0xfc,
> [BRCMNAND_CORR_COUNT] = 0x100,
> + [BRCMNAND_READ_ERROR_COUNT] = 0x104,
> [BRCMNAND_CORR_EXT_ADDR] = 0x10c,
> [BRCMNAND_CORR_ADDR] = 0x110,
> [BRCMNAND_UNCORR_EXT_ADDR] = 0x114,
> @@ -509,6 +514,7 @@ static const u16 brcmnand_regs_v71[] = {
> [BRCMNAND_CORR_THRESHOLD_EXT] = 0xe0,
> [BRCMNAND_UNCORR_COUNT] = 0xfc,
> [BRCMNAND_CORR_COUNT] = 0x100,
> + [BRCMNAND_READ_ERROR_COUNT] = 0x104,
> [BRCMNAND_CORR_EXT_ADDR] = 0x10c,
> [BRCMNAND_CORR_ADDR] = 0x110,
> [BRCMNAND_UNCORR_EXT_ADDR] = 0x114,
> @@ -539,6 +545,7 @@ static const u16 brcmnand_regs_v72[] = {
> [BRCMNAND_CORR_THRESHOLD_EXT] = 0xe0,
> [BRCMNAND_UNCORR_COUNT] = 0xfc,
> [BRCMNAND_CORR_COUNT] = 0x100,
> + [BRCMNAND_READ_ERROR_COUNT] = 0x104,
> [BRCMNAND_CORR_EXT_ADDR] = 0x10c,
> [BRCMNAND_CORR_ADDR] = 0x110,
> [BRCMNAND_UNCORR_EXT_ADDR] = 0x114,
> @@ -959,11 +966,11 @@ static inline u16 brcmnand_cs_offset(struct brcmnand_controller *ctrl, int cs,
> return offs_cs0 + cs * ctrl->reg_spacing + cs_offs;
> }
>
> -static inline u32 brcmnand_count_corrected(struct brcmnand_controller *ctrl)
> +static inline u32 brcmnand_corr_total(struct brcmnand_controller *ctrl)
> {
> - if (ctrl->nand_version < 0x0600)
> - return 1;
> - return brcmnand_read_reg(ctrl, BRCMNAND_CORR_COUNT);
> + if (ctrl->nand_version < 0x400)
> + return 0;
> + return brcmnand_read_reg(ctrl, BRCMNAND_READ_ERROR_COUNT);
> }
>
> static void brcmnand_wr_corr_thresh(struct brcmnand_host *host, u8 val)
> @@ -2066,15 +2073,20 @@ static int brcmnand_dma_trans(struct brcmnand_host *host, u64 addr, u32 *buf,
> */
> static int brcmnand_read_by_pio(struct mtd_info *mtd, struct nand_chip *chip,
> u64 addr, unsigned int trans, u32 *buf,
> - u8 *oob, u64 *err_addr)
> + u8 *oob, u64 *err_addr, unsigned int *corr)
> {
> struct brcmnand_host *host = nand_get_controller_data(chip);
> struct brcmnand_controller *ctrl = host->ctrl;
> int i, ret = 0;
> + unsigned int prev_corr;
> +
> + if (corr)
> + *corr = 0;
>
> brcmnand_clear_ecc_addr(ctrl);
>
> for (i = 0; i < trans; i++, addr += FC_BYTES) {
> + prev_corr = brcmnand_corr_total(ctrl);
> brcmnand_set_cmd_addr(mtd, addr);
> /* SPARE_AREA_READ does not use ECC, so just use PAGE_READ */
> brcmnand_send_cmd(host, CMD_PAGE_READ);
> @@ -2099,13 +2111,16 @@ static int brcmnand_read_by_pio(struct mtd_info *mtd, struct nand_chip *chip,
>
> if (*err_addr)
> ret = -EBADMSG;
> - }
> + else {
> + *err_addr = brcmnand_get_correcc_addr(ctrl);
>
> - if (!ret) {
> - *err_addr = brcmnand_get_correcc_addr(ctrl);
> + if (*err_addr) {
> + ret = -EUCLEAN;
>
> - if (*err_addr)
> - ret = -EUCLEAN;
> + if (corr && (brcmnand_corr_total(ctrl) - prev_corr) > *corr)
> + *corr = brcmnand_corr_total(ctrl) - prev_corr;
> + }
> + }
> }
> }
>
> @@ -2173,6 +2188,8 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,
> int err;
> bool retry = true;
> bool edu_err = false;
> + unsigned int corrected = 0; /* max corrected bits per subpage */
> + unsigned int prev_tot = brcmnand_corr_total(ctrl);
>
> dev_dbg(ctrl->dev, "read %llx -> %p\n", (unsigned long long)addr, buf);
>
> @@ -2200,9 +2217,11 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,
> memset(oob, 0x99, mtd->oobsize);
>
> err = brcmnand_read_by_pio(mtd, chip, addr, trans, buf,
> - oob, &err_addr);
> + oob, &err_addr, &corrected);
> }
>
> + mtd->ecc_stats.corrected += brcmnand_corr_total(ctrl) - prev_tot;
> +
> if (mtd_is_eccerr(err)) {
> /*
> * On controller version and 7.0, 7.1 , DMA read after a
> @@ -2240,16 +2259,20 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,
> }
>
> if (mtd_is_bitflip(err)) {
> - unsigned int corrected = brcmnand_count_corrected(ctrl);
> -
> /* in case of EDU correctable error we read again using PIO */
> if (edu_err)
> err = brcmnand_read_by_pio(mtd, chip, addr, trans, buf,
> - oob, &err_addr);
> + oob, &err_addr, &corrected);
>
> dev_dbg(ctrl->dev, "corrected error at 0x%llx\n",
> (unsigned long long)err_addr);
> - mtd->ecc_stats.corrected += corrected;
> + /*
> + * if flipped bits accumulator is not supported but we detected
> + * a correction, increase stat by 1 to match previous behavior.
> + */
> + if (brcmnand_corr_total(ctrl) == prev_tot)
> + mtd->ecc_stats.corrected++;
> +
> /* Always exceed the software-imposed threshold */
> return max(mtd->bitflip_threshold, corrected);
> }
> --
> 2.43.5
>
Reviewed-by: William Zhang <william.zhang at broadcom.com>
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