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SubjectRe: [PATCH v2] mtd: rawnand: Add Macronix NAND read retry support
Hi Mason,

Mason Yang <masonccyang@mxic.com.tw> wrote on Fri, 17 May 2019 14:53:21
+0800:

> Add support for Macronix NAND read retry.
>
> Macronix NANDs support specific read operation for data recovery,
> which can be enabled/disabled with a SET/GET_FEATURE.
> Driver checks byte 167 of Vendor Blocks in ONFI parameter page table
> to see if this high-reliability function is supported.
>
> Signed-off-by: Mason Yang <masonccyang@mxic.com.tw>
> ---
> drivers/mtd/nand/raw/nand_macronix.c | 57 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 57 insertions(+)
>
> diff --git a/drivers/mtd/nand/raw/nand_macronix.c b/drivers/mtd/nand/raw/nand_macronix.c
> index e287e71..1a4dc92 100644
> --- a/drivers/mtd/nand/raw/nand_macronix.c
> +++ b/drivers/mtd/nand/raw/nand_macronix.c
> @@ -17,6 +17,62 @@
>
> #include "internals.h"
>
> +#define MACRONIX_READ_RETRY_BIT BIT(0)
> +#define MACRONIX_READ_RETRY_MODE 6

Can you name this define MACRONIX_NUM_READ_RETRY_MODES?

> +
> +struct nand_onfi_vendor_macronix {
> + u8 reserved[1];

Do you need this "[1]" ?

> + u8 reliability_func;
> +} __packed;
> +
> +/*
> + * Macronix NANDs support using SET/GET_FEATURES to enter/exit read retry mode
> + */
> +static int macronix_nand_setup_read_retry(struct nand_chip *chip, int mode)
> +{
> + u8 feature[ONFI_SUBFEATURE_PARAM_LEN];
> + int ret, feature_addr = ONFI_FEATURE_ADDR_READ_RETRY;
> +
> + if (chip->parameters.supports_set_get_features &&
> + test_bit(feature_addr, chip->parameters.set_feature_list) &&
> + test_bit(feature_addr, chip->parameters.get_feature_list)) {
> + feature[0] = mode;
> + ret = nand_set_features(chip, feature_addr, feature);
> + if (ret)
> + pr_err("Failed to set read retry moded:%d\n", mode);

Do you have to call nand_get_features() on error?

> +
> + ret = nand_get_features(chip, feature_addr, feature);
> + if (ret || feature[0] != mode)
> + pr_err("Failed to verify read retry moded:%d(%d)\n",
> + mode, feature[0]);

if ret == 0 but feature[0] != mode, shouldn't you return an error?

> + }
> +
> + return ret;

This will produce a Warning at compile time (ret may be used
uninitialized). Have you tested it?

> +}
> +
> +static void macronix_nand_onfi_init(struct nand_chip *chip)
> +{
> + struct nand_parameters *p = &chip->parameters;
> + struct nand_onfi_vendor_macronix *mxic;
> +
> + if (!p->onfi)
> + return;
> +
> + mxic = (struct nand_onfi_vendor_macronix *)p->onfi->vendor;
> + if ((mxic->reliability_func & MACRONIX_READ_RETRY_BIT) == 0)
> + return;
> +
> + chip->read_retries = MACRONIX_READ_RETRY_MODE;
> + chip->setup_read_retry = macronix_nand_setup_read_retry;
> +
> + if (p->supports_set_get_features) {
> + bitmap_set(p->set_feature_list,
> + ONFI_FEATURE_ADDR_READ_RETRY, 1);
> + bitmap_set(p->get_feature_list,
> + ONFI_FEATURE_ADDR_READ_RETRY, 1);
> + }
> +}
> +
> /*
> * Macronix AC series does not support using SET/GET_FEATURES to change
> * the timings unlike what is declared in the parameter page. Unflag
> @@ -65,6 +121,7 @@ static int macronix_nand_init(struct nand_chip *chip)
> chip->options |= NAND_BBM_FIRSTPAGE | NAND_BBM_SECONDPAGE;
>
> macronix_nand_fix_broken_get_timings(chip);
> + macronix_nand_onfi_init(chip);
>
> return 0;
> }


Thanks,
Miquèl

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