Re: [PATCH v3] gpio: omap: handle pin config bias flags

[Drew Fustini <drew@beagleboard.org>]

On Mon, Jul 20, 2020 at 05:38:51PM -0500, Gustavo A. R. Silva wrote:
> Hi Drew,
> 
> Somehow I ran into this patch in Linus' tree:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio.git/commit/?h=for-next&id=75dec56710dfafd37daa95e756c5d1840932ba90
> 
> Please, see some comments below...
> 
> On 7/17/20 14:40, Drew Fustini wrote:
> > Modify omap_gpio_set_config() to handle pin config bias flags by calling
> > gpiochip_generic_config().
> > 
> > The pin group for the gpio line must have the corresponding pinconf
> > properties:
> > 
> > PIN_CONFIG_BIAS_PULL_UP requires "pinctrl-single,bias-pullup"
> > PIN_CONFIG_BIAS_PULL_DOWN requires "pinctrl-single,bias-pulldown"
> > 
> > This is necessary for pcs_pinconf_set() to find the requested bias
> > parameter in the PIN_MAP_TYPE_CONFIGS_GROUP pinctrl map.
> > 
> > Signed-off-by: Drew Fustini <drew@beagleboard.org>
> > Acked-by: Grygorii Strashko <grygorii.strashko@ti.com>
> > Acked-by: Tony Lindgren <tony@atomide.com>
> > Link: https://lore.kernel.org/r/20200715213738.1640030-1-drew@beagleboard.org
> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> > ---
> >  drivers/gpio/gpio-omap.c | 16 +++++++++++-----
> >  1 file changed, 11 insertions(+), 5 deletions(-)
> > 
> > v3 changes:
> > - adjust the braces to match the correct coding style
> > - note: I originally re-submitted this as v2 by accident when it should
> >   have been v3. Sorry for the noise.
> > 
> > v2 changes:
> > - simplify handling of -ENOTSUPP return value per Grygorii's suggestion
> > 
> > diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> > index b8e2ecc3eade..0ccb31de0b67 100644
> > --- a/drivers/gpio/gpio-omap.c
> > +++ b/drivers/gpio/gpio-omap.c
> > @@ -896,12 +896,18 @@ static int omap_gpio_set_config(struct gpio_chip *chip, unsigned offset,
> >  				unsigned long config)
> >  {
> >  	u32 debounce;
> > +	int ret = -ENOTSUPP;
> > +
> > +	if ((pinconf_to_config_param(config) == PIN_CONFIG_BIAS_DISABLE) ||
> > +	    (pinconf_to_config_param(config) == PIN_CONFIG_BIAS_PULL_UP) ||
> > +	    (pinconf_to_config_param(config) == PIN_CONFIG_BIAS_PULL_DOWN)) {
> > +		ret = gpiochip_generic_config(chip, offset, config);
> > +	} else if (pinconf_to_config_param(config) == PIN_CONFIG_INPUT_DEBOUNCE) {
> > +		debounce = pinconf_to_config_argument(config);
> > +		ret = omap_gpio_debounce(chip, offset, debounce);
> > +	}
> >  
> > -	if (pinconf_to_config_param(config) != PIN_CONFIG_INPUT_DEBOUNCE)
> > -		return -ENOTSUPP;
> > -
> > -	debounce = pinconf_to_config_argument(config);
> > -	return omap_gpio_debounce(chip, offset, debounce);
> > +	return ret;
> >  }
> >  
> >  static void omap_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
> > 
> 
> Maybe next time you could consider coding something like this, instead:
> 
> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> index 8dd86b9fae53..7fbe0c9e1fc1 100644
> --- a/drivers/gpio/gpio-omap.c
> +++ b/drivers/gpio/gpio-omap.c
> @@ -899,16 +899,18 @@ static int omap_gpio_set_config(struct gpio_chip *chip, unsigned offset,
>         u32 debounce;
>         int ret = -ENOTSUPP;
> 
> -       if ((pinconf_to_config_param(config) == PIN_CONFIG_BIAS_DISABLE) ||
> -           (pinconf_to_config_param(config) == PIN_CONFIG_BIAS_PULL_UP) ||
> -           (pinconf_to_config_param(config) == PIN_CONFIG_BIAS_PULL_DOWN))
> -       {
> +       switch (pinconf_to_config_param(config)) {
> +       case PIN_CONFIG_BIAS_DISABLE:
> +       case PIN_CONFIG_BIAS_PULL_UP:
> +       case PIN_CONFIG_BIAS_PULL_DOWN:
>                 ret = gpiochip_generic_config(chip, offset, config);
> -       }
> -       else if (pinconf_to_config_param(config) == PIN_CONFIG_INPUT_DEBOUNCE)
> -       {
> +               break;
> +       case PIN_CONFIG_INPUT_DEBOUNCE:
>                 debounce = pinconf_to_config_argument(config);
>                 ret = omap_gpio_debounce(chip, offset, debounce);
> +               break;
> +       default:
> +               break;
>         }
> 
>         return ret;
> 
> It looks a bit more readable and cleaner. :)
> 
> Thanks
> --
> Gustavo

Gustavo - thanks very much for the feedback.  I appreciate getting these
insights into best practices.

Linus - should I submit a patch?

I'm not sure if it is better to limit churn, or make sure the code is
structured as best is possible.

Thanks,
Drew