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Message-ID: <2ad8d401c6c76f5233ba0bec43217b311e2a2f76.camel@svanheule.net>
Date: Sun, 23 May 2021 23:19:22 +0200
From: Sander Vanheule <sander@...nheule.net>
To: Michael Walle <michael@...le.cc>
Cc: Pavel Machek <pavel@....cz>, Rob Herring <robh+dt@...nel.org>,
Lee Jones <lee.jones@...aro.org>,
Mark Brown <broonie@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J . Wysocki" <rafael@...nel.org>,
Linus Walleij <linus.walleij@...aro.org>,
Bartosz Golaszewski <bgolaszewski@...libre.com>,
linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
linux-gpio@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
Andy Shevchenko <andy.shevchenko@...il.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/7] gpio: regmap: Add configurable dir/value order
Hi Michael,
On Tue, 2021-05-18 at 10:39 +0200, Michael Walle wrote:
> Hi,
>
> Am 2021-05-17 21:28, schrieb Sander Vanheule:
> > GPIO chips may not support setting the output value when a pin is
> > configured as an input, although the current implementation assumes
> > this
> > is always possible.
> >
> > Add support for setting pin direction before value. The order defaults
> > to setting the value first, but this can be reversed by setting the
> > regmap_config.no_set_on_input flag, similar to the corresponding flag
> > in
> > the gpio-mmio driver.
> >
> > Signed-off-by: Sander Vanheule <sander@...nheule.net>
> > ---
> > drivers/gpio/gpio-regmap.c | 20 +++++++++++++++++---
> > include/linux/gpio/regmap.h | 3 +++
> > 2 files changed, 20 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
> > index 134cedf151a7..1cdb20f8f8b4 100644
> > --- a/drivers/gpio/gpio-regmap.c
> > +++ b/drivers/gpio/gpio-regmap.c
> > @@ -170,14 +170,25 @@ static int gpio_regmap_direction_input(struct
> > gpio_chip *chip,
> > return gpio_regmap_set_direction(chip, offset, false);
> > }
> >
> > -static int gpio_regmap_direction_output(struct gpio_chip *chip,
> > - unsigned int offset, int value)
> > +static int gpio_regmap_dir_out_val_first(struct gpio_chip *chip,
> > + unsigned int offset, int value)
>
> Can we leave the name as is? TBH I find these two similar names
> super confusing. Maybe its just me, though.
Sure. This is the implementation used in gpio-mmio.c to provide the same
functionality, so I had used that for consistenty between the two drivers.
> > {
> > gpio_regmap_set(chip, offset, value);
> >
> > return gpio_regmap_set_direction(chip, offset, true);
> > }
> >
> > +static int gpio_regmap_dir_out_dir_first(struct gpio_chip *chip,
> > + unsigned int offset, int value)
> > +{
> > + int err;
>
> use ret for consistency here
>
> > +
> > + err = gpio_regmap_set_direction(chip, offset, true);
> > + gpio_regmap_set(chip, offset, value);
> > +
> > + return err;
> > +}
> > +
>
> Instead of adding a new one, we can also just check no_set_on_input
> in gpio_regmap_direction_output(), which I'd prefer.
>
> static int gpio_regmap_direction_output(struct gpio_chip *chip,
> unsigned int offset, int value)
> {
> struct gpio_regmap *gpio = gpiochip_get_data(chip);
> int ret;
>
> if (gpio->no_set_on_input) {
> /* some smart comment here, also mention gliches */
> ret = gpio_regmap_set_direction(chip, offset, true);
> gpio_regmap_set(chip, offset, value);
> } else {
> gpio_regmap_set(chip, offset, value);
> ret = gpio_regmap_set_direction(chip, offset, true);
> }
>
> return ret;
> }
>
This would certainly make the code a bit easier to follow when you're not
familiar with it :-)
I also see the other functions do checks on static values too, so I'll bring
this function in line with that style.
> > void gpio_regmap_set_drvdata(struct gpio_regmap *gpio, void *data)
> > {
> > gpio->driver_data = data;
> > @@ -277,7 +288,10 @@ struct gpio_regmap *gpio_regmap_register(const
> > struct gpio_regmap_config *config
> > if (gpio->reg_dir_in_base || gpio->reg_dir_out_base) {
> > chip->get_direction = gio_regmap_get_direction;
> > chip->direction_input = gpio_regmap_direction_input;
> > - chip->direction_output = gpio_regmap_direction_output;
> > + if (config->no_set_on_input)
> > + chip->direction_output =
> > gpio_regmap_dir_out_dir_first;
> > + else
> > + chip->direction_output =
> > gpio_regmap_dir_out_val_first;
> > }
> >
> > ret = gpiochip_add_data(chip, gpio);
> > diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
> > index 334dd928042b..2a732f8f23be 100644
> > --- a/include/linux/gpio/regmap.h
> > +++ b/include/linux/gpio/regmap.h
> > @@ -30,6 +30,8 @@ struct regmap;
> > * @reg_dir_out_base: (Optional) out setting register base address
> > * @reg_stride: (Optional) May be set if the registers (of
> > the
> > * same type, dat, set, etc) are not consecutive.
> > + * @no_set_on_input: Set if output value can only be set when the
> > direction
> > + * is configured as output.
>
> set_direction_first ?
This negation can indeed be a bit confusing, I'll change this. As Andy
suggested, I just went for a 'quirks' field, with currently only one defined
flag.
Best,
Sander
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