Re: [PATCH v2 3/3] pinctrl: da9062: add driver support

[Marco Felsch <m.felsch@xxxxxxxxxxxxxx>]

Hi Linus,

On 19-11-27 14:49, Linus Walleij wrote:
> Hi Marco,
> 
> thanks for your patch!

thanks for your fast response.

> On Wed, Nov 27, 2019 at 12:56 PM Marco Felsch <m.felsch@xxxxxxxxxxxxxx> wrote:
> 
> > The DA9062 is a mfd pmic device which supports 5 GPIOs. The GPIOs can
> > be used as input, output or have a special use-case.
> >
> > The patch adds the support for the normal input/output use-case.
> >
> > Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
> (...)
> 
> > +config PINCTRL_DA9062
> > +       tristate "Dialog Semiconductor DA9062 PMIC pinctrl and GPIO Support"
> > +       depends on MFD_DA9062
> > +       select GPIOLIB
> 
> Hm this would be one of those that could use GENERIC_REGMAP_GPIO
> the day we invent it but we haven't invented it yet.

Yes it is. Is there a plan for GENERIC_REGMAP_GPIO?

> > +#include <../gpio/gpiolib.h>
> 
> Put a comment above this telling us why you do this thing.

Okay.

> > +static int da9062_gpio_get(struct gpio_chip *gc, unsigned int offset)
> > +{
> (...)
> > +       return val & BIT(offset);
> 
> You should #include <linux/bits.h> since you use BIT()

Argh.. of course I will add the include.

> Usually I clamp it like this:
> return !!(val & BIT(offset));

Okay, I can change that too.

> > +static int da9062_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
> > +{
> > +       struct da9062_pctl *pctl = gpiochip_get_data(gc);
> > +       struct regmap *regmap = pctl->da9062->regmap;
> > +       int gpio_mode;
> > +
> > +       gpio_mode = da9062_pctl_get_pin_mode(regmap, offset);
> > +       if (gpio_mode < 0)
> > +               return gpio_mode;
> > +
> > +       switch (gpio_mode) {
> > +       case DA9062_PIN_ALTERNATE:
> > +               return -ENOTSUPP;
> > +       case DA9062_PIN_GPI:
> > +               return 1;
> > +       case DA9062_PIN_GPO_OD:
> > +       case DA9062_PIN_GPO_PP:
> > +               return 0;
> 
> We recently added defines for these directions in
> <linux/gpio/driver.h>:
> 
> #define GPIO_LINE_DIRECTION_IN  1
> #define GPIO_LINE_DIRECTION_OUT 0
> 
> Please use these. (Soon in Torvald's tree, else
> in my "devel" branch.)

I rebased it onto your devel, thanks for the hint.

> > +static int da9062_gpio_direction_input(struct gpio_chip *gc,
> > +                                      unsigned int offset)
> > +{
> > +       struct da9062_pctl *pctl = gpiochip_get_data(gc);
> > +       struct regmap *regmap = pctl->da9062->regmap;
> > +       struct gpio_desc *desc = gpiochip_get_desc(gc, offset);
> > +       unsigned int gpi_type;
> > +       int ret;
> > +
> > +       ret = da9062_pctl_set_pin_mode(regmap, offset, DA9062_PIN_GPI);
> > +       if (ret)
> > +               return ret;
> > +
> > +       /*
> > +        * If the gpio is active low we should set it in hw too. No worries
> > +        * about gpio_get() because we read and return the gpio-level. So the
> > +        * gpiolib active_low handling is still correct.
> > +        *
> > +        * 0 - active low, 1 - active high
> > +        */
> > +       gpi_type = !gpiod_is_active_low(desc);
> 
> That's interesting. Correct too, I guess.

Double checked it again and the datasheet calls it gpio-level so I
assume that this is correct.

> > +static int da9062_gpio_direction_output(struct gpio_chip *gc,
> > +                                       unsigned int offset, int value)
> > +{
> > +       /* Push-Pull / Open-Drain options are configured during set_config */
> > +       da9062_gpio_set(gc, offset, value);
> 
> That looks dangerous. There is no guarantee that .set_config()
> always gets called.

Hm.. it seems that other drivers using this assumption too:
  - gpio-lp87565.c
  - gpio-tps65218.c
  - ...

But you're right I missed the possible users of
gpiod_direction_output_raw().

> Please create a local state container for the mode of each pin in
> struct da9062_pctl and set it to push-pull by default at probe, then
> set this to whatever the state is here and let the .set_config()
> alter it later if need be.
> 
> If we don't do that you will get boot-time defaults I think and that
> might create bugs.

I will add a container for each pin, thanks for covering that.

> > +static int da9062_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
> > +                                 unsigned long config)
> > +{
> (...)
> > +       case PIN_CONFIG_DRIVE_OPEN_DRAIN:
> > +               return da9062_pctl_set_pin_mode(regmap, offset,
> > +                                               DA9062_PIN_GPO_OD);
> > +       case PIN_CONFIG_DRIVE_PUSH_PULL:
> > +               return da9062_pctl_set_pin_mode(regmap, offset,
> > +                                               DA9062_PIN_GPO_PP);
> 
> So also store this in the per-pin state.

Of course.

Regards,
  Marco

> 
> Yours,
> Linus Walleij
> 

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