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Message-ID: <20151102003733.GA677@laptop.cereza>
Date: Sun, 1 Nov 2015 21:37:33 -0300
From: Ezequiel Garcia <ezequiel@...guardiasur.com.ar>
To: Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc: David Woodhouse <dwmw2@...radead.org>,
Brian Norris <computersforpeace@...il.com>,
linux-mtd@...ts.infradead.org,
Maxime Ripard <maxime.ripard@...e-electrons.com>,
linux-sunxi@...glegroups.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] mtd: nand: automate NAND timings selection
Hi Boris,
This looks nice. I gave a try at this patch and it allows to simplify
pxa3xx-nand greatly. A few comments below.
On 23 Oct 01:03 PM, Boris Brezillon wrote:
> The NAND framework provides several helpers to query timing modes supported
> by a NAND chip, but this implies that all NAND controller drivers have
> to implement the same timings selection dance.
>
> Provide a common logic to select the best timings based on ONFI or
> ->onfi_timing_mode_default information.
> NAND controller willing to support timings adjustment should just
> implement the ->setup_data_interface() method.
>
> Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
> ---
> drivers/mtd/nand/nand_base.c | 189 ++++++++++++++++++++++++++++++++++++++++++-
> include/linux/mtd/nand.h | 115 +++++++++++++++-----------
> 2 files changed, 254 insertions(+), 50 deletions(-)
>
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index eaf1fcd..52a1f89 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -3323,6 +3323,144 @@ static void nand_onfi_detect_micron(struct nand_chip *chip,
> chip->setup_read_retry = nand_setup_read_retry_micron;
> }
>
> +/**
> + * nand_setup_data_interface - Setup the data interface and timings on the
> + * controller side
> + * @mtd: MTD device structure
> + * @conf: new configuration to apply
> + *
> + * Try to configure the NAND controller to support the provided data
> + * interface configuration.
> + *
> + * Returns 0 in case of success or -ERROR_CODE.
> + */
> +static int nand_setup_data_interface(struct mtd_info *mtd,
> + const struct nand_data_interface *conf)
> +{
> + struct nand_chip *chip = mtd->priv;
> + int ret;
> +
> + if (!chip->setup_data_interface)
> + return -ENOTSUPP;
> +
> + ret = chip->setup_data_interface(mtd, conf, false);
> + if (ret)
> + return ret;
> +
> + *chip->data_iface = *conf;
> +
> + return 0;
> +}
> +
> +/**
> + * nand_setup_data_interface - Check if a data interface config is supported
s/setup/check
> + * by the NAND controller
> + * @mtd: MTD device structure
> + * @conf: new configuration to apply
> + *
> + * Check if the provided data interface configuration is supported by the
> + * NAND controller.
> + *
> + * Returns 0 if it is supported or -ERROR_CODE.
> + */
> +static int nand_check_data_interface(struct mtd_info *mtd,
> + const struct nand_data_interface *conf)
> +{
> + struct nand_chip *chip = mtd->priv;
> +
> + if (!chip->setup_data_interface)
> + return -ENOTSUPP;
> +
> + return chip->setup_data_interface(mtd, conf, true);
> +}
> +
> +/**
> + * nand_configure_data_interface - Configure the data interface and timings
> + * @mtd: MTD device structure
> + *
> + * Try to configure the data interface and NAND timings appropriately.
> + * First tries to retrieve supported timing modes from ONFI information,
> + * and if the NAND chip does not support ONFI, relies on the
> + * ->onfi_timing_mode_default specified in the nand_ids table.
> + *
> + * Returns 0 in case of success or -ERROR_CODE.
> + */
> +static int nand_configure_data_interface(struct mtd_info *mtd)
> +{
> + struct nand_chip *chip = mtd->priv;
> + struct nand_data_interface *conf;
> + int modes, mode, ret = -EINVAL;
> +
> + conf = kzalloc(sizeof(*conf), GFP_KERNEL);
> + if (!conf)
> + return -ENOMEM;
> +
> + /* TODO: support DDR interfaces */
> + conf->type = NAND_SDR_IFACE;
> +
> + /*
> + * First try to identify the best timings from ONFI parameters and
> + * if the NAND does not support ONFI, fallback to the default ONFI
> + * timing mode.
> + */
> + modes = onfi_get_async_timing_mode(chip);
> + if (modes != ONFI_TIMING_MODE_UNKNOWN) {
> + for (mode = fls(modes) - 1; mode >= 0; mode--) {
> + conf->timings.sdr =
> + *onfi_async_timing_mode_to_sdr_timings(mode);
> +
> + ret = nand_check_data_interface(mtd, conf);
> + if (!ret)
> + break;
> + }
> + } else {
> + mode = chip->onfi_timing_mode_default;
> + conf->timings.sdr =
> + *onfi_async_timing_mode_to_sdr_timings(mode);
> +
> + ret = nand_check_data_interface(mtd, conf);
> + }
> +
> + if (!ret) {
> + uint8_t tmode_param[ONFI_SUBFEATURE_PARAM_LEN] = { mode };
> + int i;
> +
> + /*
> + * Ensure the timing mode has be changed on the chip side
> + * before changing timings on the controller side.
> + */
> + if (modes != ONFI_TIMING_MODE_UNKNOWN) {
> + /*
> + * FIXME: should we really set the timing mode on all
> + * dies?
> + */
> + for (i = 0; i < chip->numchips; i++) {
> + chip->select_chip(mtd, i);
> + ret = chip->onfi_set_features(mtd, chip,
> + ONFI_FEATURE_ADDR_TIMING_MODE,
> + tmode_param);
> + }
> + chip->select_chip(mtd, -1);
> + }
> +
> + if (!ret) {
> + ret = nand_setup_data_interface(mtd, conf);
> +
> + /*
> + * Reset the NAND chip if the data interface setup
> + * failed so that the chip goes back to a known state
> + * (timing mode 0).
> + */
> + if (ret)
> + chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);
> + }
> + }
> +
> + kfree(conf);
> +
> + return ret;
> +}
> +
> /*
> * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise.
> */
> @@ -3906,6 +4044,11 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
> chip->options &= ~NAND_SAMSUNG_LP_OPTIONS;
> ident_done:
>
> + /*
> + * Setup the NAND interface (interface type + timings).
> + */
> + nand_configure_data_interface(mtd);
> +
Need to check the returned value.
Also, it doesn't feel right to configure the timings in nand_get_flash_type.
How about something like this:
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 947e74d24ee8..5fae81101c32 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -4009,11 +4009,6 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
chip->options &= ~NAND_SAMSUNG_LP_OPTIONS;
ident_done:
- /*
- * Setup the NAND interface (interface type + timings).
- */
- nand_configure_data_interface(mtd);
-
/* Try to identify manufacturer */
for (maf_idx = 0; nand_manuf_ids[maf_idx].id != 0x0; maf_idx++) {
if (nand_manuf_ids[maf_idx].id == *maf_id)
@@ -4189,6 +4184,13 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips,
goto err;
}
+ /*
+ * Setup the NAND interface (interface type + timings).
+ */
+ ret = nand_configure_data_interface(mtd);
+ if (ret)
+ return ret;
+
chip->select_chip(mtd, -1);
[..]
> /* Try to identify manufacturer */
> for (maf_idx = 0; nand_manuf_ids[maf_idx].id != 0x0; maf_idx++) {
> if (nand_manuf_ids[maf_idx].id == *maf_id)
> @@ -4033,6 +4176,41 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips,
> /* Set the default functions */
> nand_set_defaults(chip, chip->options & NAND_BUSWIDTH_16);
>
> + /*
> + * Allocate an interface config struct if the controller implements the
> + * ->apply_interface_conf() method.
> + */
> + if (chip->setup_data_interface) {
> + chip->data_iface = kzalloc(sizeof(*chip->data_iface),
> + GFP_KERNEL);
> + if (!chip->data_iface)
> + return -ENOMEM;
> +
> + /*
> + * The ONFI specification says:
> + * "
> + * To transition from NV-DDR or NV-DDR2 to the SDR data
> + * interface, the host shall use the Reset (FFh) command
> + * using SDR timing mode 0. A device in any timing mode is
> + * required to recognize Reset (FFh) command issued in SDR
> + * timing mode 0.
> + * "
> + *
> + * Configure the data interface in SDR mode and set the
> + * timings to timing mode 0. The Reset command is issued
> + * in nand_get_flash_type().
> + */
> +
> + chip->data_iface->type = NAND_SDR_IFACE;
> + chip->data_iface->timings.sdr =
> + *onfi_async_timing_mode_to_sdr_timings(0);
> + ret = chip->setup_data_interface(mtd, chip->data_iface, false);
> + if (ret) {
> + pr_err("Failed to configure data interface to SDR timing mode 0\n");
> + goto err;
> + }
> + }
> +
> /* Read the flash type */
> type = nand_get_flash_type(mtd, chip, &nand_maf_id,
> &nand_dev_id, table);
> @@ -4041,7 +4219,9 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips,
> if (!(chip->options & NAND_SCAN_SILENT_NODEV))
> pr_warn("No NAND device found\n");
> chip->select_chip(mtd, -1);
> - return PTR_ERR(type);
> + kfree(chip->data_iface);
You free data_iface here...
> + ret = PTR_ERR(type);
> + goto err;
> }
>
> chip->select_chip(mtd, -1);
> @@ -4069,6 +4249,10 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips,
> mtd->size = i * chip->chipsize;
>
> return 0;
> +
> +err:
> + kfree(chip->data_iface);
...and again here.
> + return ret;
> }
> EXPORT_SYMBOL(nand_scan_ident);
>
> @@ -4476,6 +4660,9 @@ void nand_release(struct mtd_info *mtd)
>
> mtd_device_unregister(mtd);
>
> + /* Free interface config struct */
> + kfree(chip->data_iface);
> +
> /* Free bad block table memory */
> kfree(chip->bbt);
> if (!(chip->options & NAND_OWN_BUFFERS))
> diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
[..]
> /**
> * struct nand_chip - NAND Private Flash Chip Data
> * @IO_ADDR_R: [BOARDSPECIFIC] address to read the 8 I/O lines of the
> @@ -690,6 +750,10 @@ struct nand_chip {
> int (*onfi_get_features)(struct mtd_info *mtd, struct nand_chip *chip,
> int feature_addr, uint8_t *subfeature_para);
> int (*setup_read_retry)(struct mtd_info *mtd, int retry_mode);
> + int (*setup_data_interface)(struct mtd_info *mtd,
> + const struct nand_data_interface *conf,
> + bool check_only);
The function lacks its proper documentation in the comment above
the struct.
--
Ezequiel Garcia, VanguardiaSur
www.vanguardiasur.com.ar
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