linux-kernel - Re: [PATCH v2 2/7] gpio: regmap: Add configurable dir/value order

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Date:   Tue, 18 May 2021 13:39:22 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Michael Walle <michael@...le.cc>,
        Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
Cc:     Sander Vanheule <sander@...nheule.net>,
        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 LED Subsystem <linux-leds@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/7] gpio: regmap: Add configurable dir/value order

+Matti

On Tue, May 18, 2021 at 11:39 AM Michael Walle <michael@...le.cc> wrote:
> Am 2021-05-17 21:28, schrieb Sander Vanheule:

...

> Instead of adding a new one, we can also just check no_set_on_input
> in gpio_regmap_direction_output(), which I'd prefer.

+! here.

> 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;
> }

...

> > + * @no_set_on_input: Set if output value can only be set when the
> > direction
> > + *                   is configured as output.
>
> set_direction_first ?

Perhaps we need to establish rather something like

/* Broken hardware can't set value on input pin, we have to set it to
output first */
#define GPIO_REGMAP_QUIRK_...  BIT(0)

unsigned int quirks;

?

-- 
With Best Regards,
Andy Shevchenko