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| author | Russell King <rmk+kernel@armlinux.org.uk> | 2019-12-07 16:20:18 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-01-09 10:19:59 +0100 |
| commit | 530f7c6df94e2190ae4499633910f36487da4d6c (patch) | |
| tree | e06c330db6317094f0f472912cfac92f36b0bfe6 | |
| parent | 5654d5d25c17782e0a12554483bd345cd25b7bf6 (diff) | |
| download | linux-stable-530f7c6df94e2190ae4499633910f36487da4d6c.tar.gz linux-stable-530f7c6df94e2190ae4499633910f36487da4d6c.tar.bz2 linux-stable-530f7c6df94e2190ae4499633910f36487da4d6c.zip | |
gpiolib: fix up emulated open drain outputs
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>
| -rw-r--r-- | drivers/gpio/gpiolib.c | 8 |
1 files changed, 8 insertions, 0 deletions
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; |