3.16.83-rc1 review patch. If anyone has any objections, please let me know.
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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.
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: Ben Hutchings ben@decadent.org.uk --- drivers/gpio/gpiolib.c | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -273,6 +273,14 @@ int gpiod_get_direction(const struct gpi 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 status;