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 <675e36df5aaa1e1be3a1a77289a0a952@walle.cc>
In-Reply-To: <675e36df5aaa1e1be3a1a77289a0a952@walle.cc>
From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Tue, 18 May 2021 13:39:22 +0300
Message-ID: <CAHp75VdLwSoPpmDm1j=d9kLWzzfGsHCVvMSX-9wD+sgRzHC9oA@mail.gmail.com>
Subject: Re: [PATCH v2 2/7] gpio: regmap: Add configurable dir/value order
To:     Michael Walle <michael@walle.cc>,
        Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Cc:     Sander Vanheule <sander@svanheule.net>,
        Pavel Machek <pavel@ucw.cz>, Rob Herring <robh+dt@kernel.org>,
        Lee Jones <lee.jones@linaro.org>,
        Mark Brown <broonie@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Linux LED Subsystem <linux-leds@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        Andrew Lunn <andrew@lunn.ch>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Precedence: bulk

+Matti

On Tue, May 18, 2021 at 11:39 AM Michael Walle <michael@walle.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