| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.4 111/191] gpiolib: fix up emulated open drain outputs | Date | Tue, 7 Jan 2020 21:53:51 +0100 |
| |
From: Russell King <rmk+kernel@armlinux.org.uk>
commit 256efaea1fdc4e38970489197409a26125ee0aaa upstream.
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.
Cc: <stable@vger.kernel.org> Suggested-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/gpio/gpiolib.c | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -220,6 +220,14 @@ int gpiod_get_direction(struct gpio_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;
|