Re: [PATCH v5 17/28] mtd: rawnand: Define a unique reset data interface

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Boris,

Boris Brezillon <boris.brezillon@collabora.com> wrote on Tue, 26 May
2020 23:23:38 +0200:

> On Tue, 26 May 2020 21:17:14 +0200
> Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> 
> > All NAND chips will always use the same data interface for reset and
> > at startup: SDR mode 0. Instead of copying around the data interface
> > timings, let's just have a default reset data interface for that.
> > 
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > ---
> >  drivers/mtd/nand/raw/nand_base.c    | 9 +++------
> >  drivers/mtd/nand/raw/nand_timings.c | 3 +++
> >  include/linux/mtd/rawnand.h         | 3 +++
> >  3 files changed, 9 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> > index 89f10a8c1d62..1005035c233a 100644
> > --- a/drivers/mtd/nand/raw/nand_base.c
> > +++ b/drivers/mtd/nand/raw/nand_base.c
> > @@ -927,9 +927,8 @@ static int nand_reset_data_interface(struct nand_chip *chip, int chipnr)
> >  	 * timings to timing mode 0.
> >  	 */
> >  
> > -	onfi_fill_data_interface(chip, &chip->data_interface, NAND_SDR_IFACE, 0);
> >  	ret = chip->controller->ops->setup_data_interface(chip, chipnr,
> > -							&chip->data_interface);
> > +							  nand_reset_data_iface);
> >  	if (ret)
> >  		pr_err("Failed to configure data interface to SDR timing mode 0\n");
> >  
> > @@ -2484,7 +2483,6 @@ EXPORT_SYMBOL_GPL(nand_subop_get_data_len);
> >   */
> >  int nand_reset(struct nand_chip *chip, int chipnr)
> >  {
> > -	struct nand_data_interface saved_data_intf = chip->data_interface;
> >  	int ret;
> >  
> >  	ret = nand_reset_data_interface(chip, chipnr);
> > @@ -2509,11 +2507,10 @@ 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, &saved_data_intf,
> > -		    sizeof(saved_data_intf)))
> > +	if (!memcmp(&chip->data_interface, nand_reset_data_iface,
> > +		    sizeof(*nand_reset_data_iface)))
> >  		return 0;
> >  
> > -	chip->data_interface = saved_data_intf;
> >  	ret = nand_setup_data_interface(chip, chipnr);
> >  	if (ret)
> >  		return ret;
> > diff --git a/drivers/mtd/nand/raw/nand_timings.c b/drivers/mtd/nand/raw/nand_timings.c
> > index 52ee83e75646..343284c43e81 100644
> > --- a/drivers/mtd/nand/raw/nand_timings.c
> > +++ b/drivers/mtd/nand/raw/nand_timings.c
> > @@ -285,6 +285,9 @@ static const struct nand_data_interface onfi_sdr_timings[] = {
> >  	},
> >  };
> >  
> > +/* All NAND chips share the same reset data interface: SDR mode 0 */
> > +const struct nand_data_interface *nand_reset_data_iface = &onfi_sdr_timings[0];  
> 
> Can we make that one a function?
> 
> const struct nand_data_interface *nand_get_reset_data_interface(void)
> {
> 	return &onfi_sdr_timings[0];
> }

Sure!

> 
> > +
> >  /**
> >   * onfi_find_closest_sdr_mode - Derive the closest ONFI SDR timing mode given a
> >   *                              set of timings
> > diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
> > index 622da6527a36..6c334cca3977 100644
> > --- a/include/linux/mtd/rawnand.h
> > +++ b/include/linux/mtd/rawnand.h
> > @@ -1203,6 +1203,9 @@ static inline struct device_node *nand_get_flash_node(struct nand_chip *chip)
> >  	return mtd_get_of_node(nand_to_mtd(chip));
> >  }
> >  
> > +/* Default/reset data interface */
> > +extern const struct nand_data_interface *nand_reset_data_iface;
> > +
> >  /*
> >   * A helper for defining older NAND chips where the second ID byte fully
> >   * defined the chip, including the geometry (chip size, eraseblock size, page  
> 

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