[v2,1/2] mtd: rawnand: Add a helper for testing data interface

From: Rickard x Andersson <rickaran@axis.com>

This helper tests the current data interface timings. If
the controller does not accept the timings then the timings
are erased and onfi mode 0 timings are chosen at a later
stage.

Signed-off-by: Rickard x Andersson <rickaran@axis.com>
---
 drivers/mtd/nand/raw/internals.h |  1 +
 drivers/mtd/nand/raw/nand_base.c | 38 ++++++++++++++++++++++++++++----------
 2 files changed, 29 insertions(+), 10 deletions(-)

Hi Rickard,

Rickard Andersson <rickaran@axis.com> wrote on Wed, 20 May 2020
15:38:53 +0200:

> From: Rickard x Andersson <rickaran@axis.com>
> 
> This helper tests the current data interface timings. If
> the controller does not accept the timings then the timings

s/accept/support/

> are erased and onfi mode 0 timings are chosen at a later
> stage.

See below, I don't think this is needed.

> 
> Signed-off-by: Rickard x Andersson <rickaran@axis.com>
> ---
>  drivers/mtd/nand/raw/internals.h |  1 +
>  drivers/mtd/nand/raw/nand_base.c | 38 ++++++++++++++++++++++++++++----------
>  2 files changed, 29 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/internals.h b/drivers/mtd/nand/raw/internals.h
> index 615677820338..7df0a8e674cb 100644
> --- a/drivers/mtd/nand/raw/internals.h
> +++ b/drivers/mtd/nand/raw/internals.h
> @@ -100,6 +100,7 @@ int nand_read_param_page_op(struct nand_chip *chip, u8 page, void *buf,
>  void nand_decode_ext_id(struct nand_chip *chip);
>  void panic_nand_wait(struct nand_chip *chip, unsigned long timeo);
>  void sanitize_string(uint8_t *s, size_t len);
> +int nand_test_data_interface(struct nand_chip *chip);
>  
>  static inline bool nand_has_exec_op(struct nand_chip *chip)
>  {
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index c42cbeb7e446..29e7be3811e7 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -956,6 +956,32 @@ static int nand_setup_data_interface(struct nand_chip *chip, int chipnr)
>  }
>  
>  /**
> + * nand_test_data_interface - Check if controller can handle the current

I'm fine adding an helper for that. It could also be used for DDR timing
support.

What about renaming it "nand_controller_supports_data_interface()"?

> + * timings. Clear timings if not usable.
> + *
> + * @chip: The NAND chip
> + */
> +int nand_test_data_interface(struct nand_chip *chip)
> +{
> +	int ret;

Missing extra line

> +	/*
> +	 * Pass NAND_DATA_IFACE_CHECK_ONLY to only check if the
> +	 * controller supports the requested timings.
> +	 */
> +	ret = chip->controller->ops->setup_data_interface(chip,
> +						 NAND_DATA_IFACE_CHECK_ONLY,
> +						 &chip->data_interface);

Could you align these lines to the opened parenthesis?

> +
> +	if (ret) {
> +		/* The provided data interface timings did not work */
> +		memset(&chip->data_interface, 0,
> +		       sizeof(struct nand_data_interface));

I'm not sure this is needed. I think it will only be necessary in your
case, so I think it's better to move it ouf of this function.

> +	}
> +
> +	return ret;
> +}

Maybe it is best to move this function in internals.h directly.

> +
> +/**
>   * nand_choose_data_interface - find the best data interface and timings
>   * @chip: The NAND chip
>   *
> @@ -994,9 +1020,6 @@ static int nand_choose_data_interface(struct nand_chip *chip)
>  	if (chip->parameters.onfi) {
>  		modes = chip->parameters.onfi->async_timing_mode;
>  	} else {
> -		if (!chip->default_timing_mode)
> -			return 0;
> -

This should not be removed

>  		modes = GENMASK(chip->default_timing_mode, 0);
>  	}
>  
> @@ -1005,13 +1028,8 @@ static int nand_choose_data_interface(struct nand_chip *chip)
>  		if (ret)
>  			continue;
>  
> -		/*
> -		 * Pass NAND_DATA_IFACE_CHECK_ONLY to only check if the
> -		 * controller supports the requested timings.
> -		 */
> -		ret = chip->controller->ops->setup_data_interface(chip,
> -						 NAND_DATA_IFACE_CHECK_ONLY,
> -						 &chip->data_interface);
> +		/* Check if the controller supports the requested timings. */
> +		ret = nand_test_data_interface(chip);
>  		if (!ret) {
>  			chip->default_timing_mode = mode;
>  			break;

Thanks,
Miquèl

Hi Miquel,

Comments on two of your comments. (I am fine with all the other comments.)

> > +     /*
> > +      * Pass NAND_DATA_IFACE_CHECK_ONLY to only check if the
> > +      * controller supports the requested timings.
> > +      */
> > +     ret = chip->controller->ops->setup_data_interface(chip,
> > +                                              NAND_DATA_IFACE_CHECK_ONLY,
> > +                                              &chip->data_interface);
>
> Could you align these lines to the opened parenthesis?

Then the lines will have 80+ characters.

> > @@ -994,9 +1020,6 @@ static int nand_choose_data_interface(struct nand_chip *chip)
> >       if (chip->parameters.onfi) {
> >               modes = chip->parameters.onfi->async_timing_mode;
> >       } else {
> > -             if (!chip->default_timing_mode)
> > -                     return 0;
> > -
>
> This should not be removed

Then onfi_fill_data_interface would not be called for default_timing_mode 0. (In case we have called chip->ops.choose_data_interface and got an error.).

BR,
Rickard

On Wed, 20 May 2020 14:52:52 +0000
Rickard X Andersson <Rickard.Andersson@axis.com> wrote:

> Hi Miquel,
> 
> Comments on two of your comments. (I am fine with all the other comments.)
> 
> > > +     /*
> > > +      * Pass NAND_DATA_IFACE_CHECK_ONLY to only check if the
> > > +      * controller supports the requested timings.
> > > +      */
> > > +     ret = chip->controller->ops->setup_data_interface(chip,
> > > +                                              NAND_DATA_IFACE_CHECK_ONLY,
> > > +                                              &chip->data_interface);  
> >
> > Could you align these lines to the opened parenthesis?  
> 
> Then the lines will have 80+ characters.

Just add a local ops var.

	const struct nand_controller_ops *ops = chip->controller->ops;

	ret = ops->setup_data_interface(chip, NAND_DATA_IFACE_CHECK_ONLY,
					 &chip->data_interface);