From: Russell King Bcc: linux@mail.armlinux.org.uk Cc: Linus Walleij ,Bartosz Golaszewski ,linux-gpio@vger.kernel.org Subject: [PATCH] gpiolib: fix up emulated open drain outputs MIME-Version: 1.0 Content-Disposition: inline Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="utf-8" gpiolib has a corner case with open drain outputs that are emulated. When such outputs are outputting a logic 1, emulation will set the hardware to input mode, which will cause gpiod_get_direction() to report that it is in input mode. This is different from the behaviour with a true open-drain output. Unify the semantics here. Suggested-by: Linus Walleij Signed-off-by: Russell King --- drivers/gpio/gpiolib.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 104ed299d5ea..99d19f80440e 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -220,6 +220,14 @@ int gpiod_get_direction(struct gpio_desc *desc) chip = gpiod_to_chip(desc); offset = gpio_chip_hwgpio(desc); + /* + * Open drain emulation using input mode may incorrectly report + * input here, fix that up. + */ + if (test_bit(FLAG_OPEN_DRAIN, &desc->flags) && + test_bit(FLAG_IS_OUT, &desc->flags)) + return 0; + if (!chip->get_direction) return -ENOTSUPP; -- 2.20.1