[RFC 03/12] mtd: nand: use a static data_interface in the nand_chip structure
Boris Brezillon
boris.brezillon at free-electrons.com
Wed Oct 18 10:02:55 PDT 2017
On Wed, 18 Oct 2017 16:36:20 +0200
Miquel Raynal <miquel.raynal at free-electrons.com> wrote:
> Change the data_interface field from the nand_chip structure, convert
> the pointer to a static structure.
You mean "embed a nand_data_interface object". Not sure the static
specifier can be used to describe what you do.
>
> Also remove the nand_get_default_data_interface() function that become
> useless and rename the onfi_init_data_interface() by
> nand_fill_data_interface(),
I know I'm the one who suggested to rename this function, but I'm not
so sure it's a good idea in the end, and I don't like the new prototype
where you drop the iface_type parameter.
> which is a more appropriate name because
> applied timings are ONFI, no matter if the NAND actually is one.
Well, this is actually a good reason to keep the onfi_ prefix. A NAND
driver can decide that its NAND is close to an existing timing mode and
re-use this onfi_init_data_interface(), but maybe someday we'll have
drivers filling the nand_data_interface object with their own
(non-ONFI) timings.
>
> This is needed before passing to ->exec_op() to avoid any race that
It's not really a race, it's just that you need some timings during
NAND detection, and the core is currently creating the
nand_data_interface object after the detection step (in
nand_scan_tail()).
> could lead to a panic (null pointer dereference) on the initialization
> of the timings structure that will be used from the first reset
> operation if the pointer to data_interface was not referenced yet.
>
> Signed-off-by: Miquel Raynal <miquel.raynal at free-electrons.com>
> ---
> drivers/mtd/nand/nand_base.c | 35 ++++++++++-------------------------
> drivers/mtd/nand/nand_timings.c | 23 ++++++-----------------
> include/linux/mtd/rawnand.h | 9 ++-------
> 3 files changed, 18 insertions(+), 49 deletions(-)
>
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index 318595c29053..bef20e06f0db 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -814,8 +814,8 @@ static void nand_ccs_delay(struct nand_chip *chip)
> * Wait tCCS_min if it is correctly defined, otherwise wait 500ns
> * (which should be safe for all NANDs).
> */
> - if (chip->data_interface && chip->data_interface->timings.sdr.tCCS_min)
> - ndelay(chip->data_interface->timings.sdr.tCCS_min / 1000);
> + if (chip->data_interface.timings.sdr.tCCS_min)
> + ndelay(chip->data_interface.timings.sdr.tCCS_min / 1000);
> else
> ndelay(500);
> }
> @@ -1107,7 +1107,6 @@ static int nand_wait(struct mtd_info *mtd, struct nand_chip *chip)
> static int nand_reset_data_interface(struct nand_chip *chip, int chipnr)
> {
> struct mtd_info *mtd = nand_to_mtd(chip);
> - const struct nand_data_interface *conf;
> int ret;
>
> if (!chip->setup_data_interface)
> @@ -1127,8 +1126,8 @@ static int nand_reset_data_interface(struct nand_chip *chip, int chipnr)
> * timings to timing mode 0.
> */
>
> - conf = nand_get_default_data_interface();
> - ret = chip->setup_data_interface(mtd, chipnr, conf);
> + nand_fill_data_interface(chip, 0);
> + ret = chip->setup_data_interface(mtd, chipnr, &chip->data_interface);
> if (ret)
> pr_err("Failed to configure data interface to SDR timing mode 0\n");
>
So now you're stuck in timing mode 0 as soon as you have nand_reset()
called.
Actually, what we should do is:
1/ at the beginning of nand_scan_ident(), call
onfi_init_data_interface(chip, &chip->data_interface, NAND_SDR_IFACE, 0)
(or a wrapper that does that) so that data_interface is initialized with
the appropriate timings for reset/detection operations
2/ after detection, find the best iface type and timing mode we can use
(what's currently done in nand_init_data_interface())
3/ in nand_reset(), you should save what's in chip->data_interface, in a
local variable, then apply SDR+timing-mode-0 and finally restore the
previous settings (the one you stored in your local variable) after
the RESET op.
This way you're guaranteed to always end up with the best data iface
settings after a RESET.
> @@ -1153,7 +1152,7 @@ static int nand_setup_data_interface(struct nand_chip *chip, int chipnr)
> struct mtd_info *mtd = nand_to_mtd(chip);
> int ret;
>
> - if (!chip->setup_data_interface || !chip->data_interface)
> + if (!chip->setup_data_interface)
> return 0;
>
> /*
> @@ -1174,7 +1173,7 @@ static int nand_setup_data_interface(struct nand_chip *chip, int chipnr)
> goto err;
> }
>
> - ret = chip->setup_data_interface(mtd, chipnr, chip->data_interface);
> + ret = chip->setup_data_interface(mtd, chipnr, &chip->data_interface);
> err:
> return ret;
> }
> @@ -1214,21 +1213,16 @@ static int nand_init_data_interface(struct nand_chip *chip)
> modes = GENMASK(chip->onfi_timing_mode_default, 0);
> }
>
> - chip->data_interface = kzalloc(sizeof(*chip->data_interface),
> - GFP_KERNEL);
> - if (!chip->data_interface)
> - return -ENOMEM;
>
> for (mode = fls(modes) - 1; mode >= 0; mode--) {
> - ret = onfi_init_data_interface(chip, chip->data_interface,
> - NAND_SDR_IFACE, mode);
> + ret = nand_fill_data_interface(chip, mode);
> if (ret)
> continue;
>
> /* Pass -1 to only */
> ret = chip->setup_data_interface(mtd,
> NAND_DATA_IFACE_CHECK_ONLY,
> - chip->data_interface);
> + &chip->data_interface);
> if (!ret) {
> chip->onfi_timing_mode_default = mode;
> break;
> @@ -1238,11 +1232,6 @@ static int nand_init_data_interface(struct nand_chip *chip)
> return 0;
> }
>
> -static void nand_release_data_interface(struct nand_chip *chip)
> -{
> - kfree(chip->data_interface);
> -}
> -
> /**
> * nand_read_page_op - Do a READ PAGE operation
> * @chip: The NAND chip
> @@ -5567,7 +5556,7 @@ int nand_scan_tail(struct mtd_info *mtd)
> chip->select_chip(mtd, -1);
>
> if (ret)
> - goto err_nand_data_iface_cleanup;
> + goto err_nand_manuf_cleanup;
> }
>
> /* Check, if we should skip the bad block table scan */
> @@ -5577,12 +5566,10 @@ int nand_scan_tail(struct mtd_info *mtd)
> /* Build bad block table */
> ret = chip->scan_bbt(mtd);
> if (ret)
> - goto err_nand_data_iface_cleanup;
> + goto err_nand_manuf_cleanup;
>
> return 0;
>
> -err_nand_data_iface_cleanup:
> - nand_release_data_interface(chip);
>
> err_nand_manuf_cleanup:
> nand_manufacturer_cleanup(chip);
> @@ -5641,8 +5628,6 @@ void nand_cleanup(struct nand_chip *chip)
> chip->ecc.algo == NAND_ECC_BCH)
> nand_bch_free((struct nand_bch_control *)chip->ecc.priv);
>
> - nand_release_data_interface(chip);
> -
> /* Free bad block table memory */
> kfree(chip->bbt);
> if (!(chip->options & NAND_OWN_BUFFERS) && chip->buffers) {
> diff --git a/drivers/mtd/nand/nand_timings.c b/drivers/mtd/nand/nand_timings.c
> index 5d1533bcc5bd..745b6404c901 100644
> --- a/drivers/mtd/nand/nand_timings.c
> +++ b/drivers/mtd/nand/nand_timings.c
> @@ -283,17 +283,17 @@ const struct nand_sdr_timings *onfi_async_timing_mode_to_sdr_timings(int mode)
> EXPORT_SYMBOL(onfi_async_timing_mode_to_sdr_timings);
>
> /**
> - * onfi_init_data_interface - [NAND Interface] Initialize a data interface from
> + * nand_fill_data_interface - [NAND Interface] Initialize a data interface from
> * given ONFI mode
> * @iface: The data interface to be initialized
> * @mode: The ONFI timing mode
> */
> -int onfi_init_data_interface(struct nand_chip *chip,
> - struct nand_data_interface *iface,
> - enum nand_data_interface_type type,
> +int nand_fill_data_interface(struct nand_chip *chip,
> int timing_mode)
> {
> - if (type != NAND_SDR_IFACE)
> + struct nand_data_interface *iface = &chip->data_interface;
> +
> + if (iface->type != NAND_SDR_IFACE)
> return -EINVAL;
>
> if (timing_mode < 0 || timing_mode >= ARRAY_SIZE(onfi_sdr_timings))
> @@ -321,15 +321,4 @@ int onfi_init_data_interface(struct nand_chip *chip,
>
> return 0;
> }
> -EXPORT_SYMBOL(onfi_init_data_interface);
> -
> -/**
> - * nand_get_default_data_interface - [NAND Interface] Retrieve NAND
> - * data interface for mode 0. This is used as default timing after
> - * reset.
> - */
> -const struct nand_data_interface *nand_get_default_data_interface(void)
> -{
> - return &onfi_sdr_timings[0];
> -}
> -EXPORT_SYMBOL(nand_get_default_data_interface);
> +EXPORT_SYMBOL(nand_fill_data_interface);
> diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
> index 04f4cfbe6c09..1acc26ed0e91 100644
> --- a/include/linux/mtd/rawnand.h
> +++ b/include/linux/mtd/rawnand.h
> @@ -917,7 +917,7 @@ struct nand_chip {
> u16 max_bb_per_die;
> u32 blocks_per_die;
>
> - struct nand_data_interface *data_interface;
> + struct nand_data_interface data_interface;
>
> int read_retries;
>
> @@ -1214,10 +1214,7 @@ static inline int onfi_get_sync_timing_mode(struct nand_chip *chip)
> return le16_to_cpu(chip->onfi_params.src_sync_timing_mode);
> }
>
> -int onfi_init_data_interface(struct nand_chip *chip,
> - struct nand_data_interface *iface,
> - enum nand_data_interface_type type,
> - int timing_mode);
> +int nand_fill_data_interface(struct nand_chip *chip, int timing_mode);
>
> /*
> * Check if it is a SLC nand.
> @@ -1258,8 +1255,6 @@ static inline int jedec_feature(struct nand_chip *chip)
>
> /* get timing characteristics from ONFI timing mode. */
> const struct nand_sdr_timings *onfi_async_timing_mode_to_sdr_timings(int mode);
> -/* get data interface from ONFI timing mode 0, used after reset. */
> -const struct nand_data_interface *nand_get_default_data_interface(void);
>
> int nand_check_erased_ecc_chunk(void *data, int datalen,
> void *ecc, int ecclen,
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