Re: [PATCH v5 28/28] mtd: rawnand: Allocate the best data interface structure dynamically

[Boris Brezillon <boris.brezillon@collabora.com>]

On Tue, 26 May 2020 21:17:25 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> Instead of manipulating the statically allocated structure and copy
> timings around, allocate one at identification time and save it in the
> nand_chip structure once it has been initialized.
> 
> This way, either there is a "best data interface" and the requested
> timings will be these, or there is none, forcing the core to use the
> default set, statically defined in the core, shared across all NAND
> chips.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  drivers/mtd/nand/raw/nand_base.c | 42 ++++++++++++++++++++++----------
>  include/linux/mtd/rawnand.h      | 13 +++++++---
>  2 files changed, 39 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index 2547136a9cd7..247bf5faaf55 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -947,7 +947,7 @@ static int nand_reset_data_interface(struct nand_chip *chip, int chipnr)
>   */
>  static int nand_setup_data_interface(struct nand_chip *chip, int chipnr)
>  {
> -	u8 mode = chip->data_interface.timings.mode;
> +	u8 mode = chip->best_iface->timings.mode;
>  	u8 tmode_param[ONFI_SUBFEATURE_PARAM_LEN] = { mode, };
>  	int ret;
>  
> @@ -966,7 +966,7 @@ static int nand_setup_data_interface(struct nand_chip *chip, int chipnr)
>  
>  	/* Change the mode on the controller side */
>  	ret = chip->controller->ops->setup_data_interface(chip, chipnr,
> -							&chip->data_interface);
> +							  chip->best_iface);
>  	if (ret)
>  		return ret;
>  
> @@ -1030,8 +1030,10 @@ int nand_choose_best_sdr_timings(struct nand_chip *chip,
>  		ret = ops->setup_data_interface(chip,
>  						NAND_DATA_IFACE_CHECK_ONLY,
>  						iface);
> -		if (!ret)
> +		if (!ret) {
> +			chip->best_iface = iface;
>  			return ret;
> +		}
>  
>  		/* Fallback to slower modes */
>  		best_mode = iface->timings.mode;
> @@ -1052,6 +1054,8 @@ int nand_choose_best_sdr_timings(struct nand_chip *chip,
>  			break;
>  	}
>  
> +	chip->best_iface = iface;
> +
>  	return 0;
>  }
>  
> @@ -1070,14 +1074,25 @@ int nand_choose_best_sdr_timings(struct nand_chip *chip,
>   */
>  static int nand_choose_data_interface(struct nand_chip *chip)
>  {
> +	struct nand_data_interface *iface;
> +	int ret;
> +
>  	if (!nand_controller_has_setup_data_iface(chip))
>  		return 0;
>  
> +	iface = kzalloc(sizeof(*iface), GFP_KERNEL);
> +	if (!iface)
> +		return -ENOMEM;
> +
>  	if (chip->ops.choose_data_interface)
> -		return chip->ops.choose_data_interface(chip,
> -						       &chip->data_interface);
> +		ret = chip->ops.choose_data_interface(chip, iface);
> +	else
> +		ret = nand_choose_best_sdr_timings(chip, iface, NULL);
>  
> -	return nand_choose_best_sdr_timings(chip, &chip->data_interface, NULL);
> +	if (ret)
> +		kfree(iface);
> +
> +	return ret;
>  }
>  
>  /**
> @@ -2514,8 +2529,7 @@ int nand_reset(struct nand_chip *chip, int chipnr)
>  	 * nand_setup_data_interface() uses ->set/get_features() which would
>  	 * fail anyway as the parameter page is not available yet.
>  	 */
> -	if (!memcmp(&chip->data_interface, nand_reset_data_iface,
> -		    sizeof(*nand_reset_data_iface)))
> +	if (!chip->best_iface)
>  		return 0;
>  

If you assign ->best_iface for mode 0 (as done above) and keep the
!chip->best_iface test that means you apply timing mode 0 twice. Not
a big deal but I wanted to point it out.

>  	ret = nand_setup_data_interface(chip, chipnr);
> @@ -5252,9 +5266,6 @@ static int nand_scan_ident(struct nand_chip *chip, unsigned int maxchips,
>  
>  	mutex_init(&chip->lock);
>  
> -	/* Enforce the right timings for reset/detection */
> -	onfi_fill_data_interface(chip, &chip->data_interface, NAND_SDR_IFACE, 0);
> -
>  	ret = nand_dt_init(chip);
>  	if (ret)
>  		return ret;
> @@ -6059,7 +6070,7 @@ static int nand_scan_tail(struct nand_chip *chip)
>  	for (i = 0; i < nanddev_ntargets(&chip->base); i++) {
>  		ret = nand_setup_data_interface(chip, i);
>  		if (ret)
> -			goto err_nanddev_cleanup;
> +			goto err_free_data_iface;
>  	}
>  
>  	/* Check, if we should skip the bad block table scan */
> @@ -6069,10 +6080,12 @@ static int nand_scan_tail(struct nand_chip *chip)
>  	/* Build bad block table */
>  	ret = nand_create_bbt(chip);
>  	if (ret)
> -		goto err_nanddev_cleanup;
> +		goto err_free_data_iface;
>  
>  	return 0;
>  
> +err_free_data_iface:
> +	kfree(chip->best_iface);
>  
>  err_nanddev_cleanup:
>  	nanddev_cleanup(&chip->base);
> @@ -6166,6 +6179,9 @@ void nand_cleanup(struct nand_chip *chip)
>  			& NAND_BBT_DYNAMICSTRUCT)
>  		kfree(chip->badblock_pattern);
>  
> +	/* Free the data interface */
> +	kfree(chip->best_iface);
> +
>  	/* Free manufacturer priv data. */
>  	nand_manufacturer_cleanup(chip);
>  
> diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
> index 00557e553827..0f215faa3072 100644
> --- a/include/linux/mtd/rawnand.h
> +++ b/include/linux/mtd/rawnand.h
> @@ -1070,7 +1070,9 @@ struct nand_manufacturer {
>   * @options: Various chip options. They can partly be set to inform nand_scan
>   *           about special functionality. See the defines for further
>   *           explanation.
> - * @data_interface: NAND interface timing information
> + * @best_iface: The best NAND data interface which fits both the NAND chip and

						^ configuration

> + *              NAND controller constraints. If unset, the default reset data
> + *              interface must be used.
>   * @bbt_erase_shift: Number of address bits in a bbt entry
>   * @bbt_options: Bad block table specific options. All options used here must
>   *               come from bbm.h. By default, these options will be copied to
> @@ -1117,7 +1119,7 @@ struct nand_chip {
>  	unsigned int options;
>  
>  	/* Data interface */
> -	struct nand_data_interface data_interface;
> +	struct nand_data_interface *best_iface;

Not sure why you rename this field, but if we go for a name update, I'd
vote for best_iface_cfg (or something that clarifies the fact that this
is the data interface configuration).

>  
>  	/* Bad block information */
>  	unsigned int bbt_erase_shift;
> @@ -1212,7 +1214,12 @@ extern const struct nand_data_interface *nand_reset_data_iface;
>  static inline const struct nand_sdr_timings *
>  nand_get_sdr_timings(struct nand_chip *chip)
>  {
> -	return nand_extract_sdr_timings(&chip->data_interface);
> +	const struct nand_data_interface *iface = chip->best_iface;
> +
> +	if (!iface)
> +		iface = nand_reset_data_iface;
> +
> +	return nand_extract_sdr_timings(iface);
>  }
>  
>  /*


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