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Commit e735244e authored by Bartosz Golaszewski's avatar Bartosz Golaszewski
Browse files

gpiolib: don't clear FLAG_IS_OUT when emulating open-drain/open-source 



When emulating open-drain/open-source by not actively driving the output
lines - we're simply changing their mode to input. This is wrong as it
will then make it impossible to change the value of such line - it's now
considered to actually be in input mode. If we want to still use the
direction_input() callback for simplicity then we need to set FLAG_IS_OUT
manually in gpiod_direction_output() and not clear it in
gpio_set_open_drain_value_commit() and
gpio_set_open_source_value_commit().

Fixes: c663e5f5 ("gpio: support native single-ended hardware drivers")
Cc: stable@vger.kernel.org
Reported-by: default avatarKent Gibson <warthog618@gmail.com>
Signed-off-by: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
parent 54ecb8f7

drivers/gpio/gpiolib.c

+19 −8
Original line number Diff line number Diff line
@@ -3070,8 +3070,10 @@ int gpiod_direction_output(struct gpio_desc *desc, int value) 
		if (!ret)

			goto set_output_value;

		/* Emulate open drain by not actively driving the line high */

		if (value)

			return gpiod_direction_input(desc);

		if (value) {

			ret = gpiod_direction_input(desc);

			goto set_output_flag;

		}

	}

	else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags)) {

		ret = gpio_set_config(gc, gpio_chip_hwgpio(desc),
@@ -3079,8 +3081,10 @@ int gpiod_direction_output(struct gpio_desc *desc, int value) 
		if (!ret)

			goto set_output_value;

		/* Emulate open source by not actively driving the line low */

		if (!value)

			return gpiod_direction_input(desc);

		if (!value) {

			ret = gpiod_direction_input(desc);

			goto set_output_flag;

		}

	} else {

		gpio_set_config(gc, gpio_chip_hwgpio(desc),

				PIN_CONFIG_DRIVE_PUSH_PULL);
@@ -3088,6 +3092,17 @@ int gpiod_direction_output(struct gpio_desc *desc, int value) 


set_output_value:

	return gpiod_direction_output_raw_commit(desc, value);



set_output_flag:

	/*

	 * When emulating open-source or open-drain functionalities by not

	 * actively driving the line (setting mode to input) we still need to

	 * set the IS_OUT flag or otherwise we won't be able to set the line

	 * value anymore.

	 */

	if (ret == 0)

		set_bit(FLAG_IS_OUT, &desc->flags);

	return ret;

}

EXPORT_SYMBOL_GPL(gpiod_direction_output);
@@ -3448,8 +3463,6 @@ static void gpio_set_open_drain_value_commit(struct gpio_desc *desc, bool value) 


	if (value) {

		ret = chip->direction_input(chip, offset);

		if (!ret)

			clear_bit(FLAG_IS_OUT, &desc->flags);

	} else {

		ret = chip->direction_output(chip, offset, 0);

		if (!ret)
@@ -3479,8 +3492,6 @@ static void gpio_set_open_source_value_commit(struct gpio_desc *desc, bool value 
			set_bit(FLAG_IS_OUT, &desc->flags);

	} else {

		ret = chip->direction_input(chip, offset);

		if (!ret)

			clear_bit(FLAG_IS_OUT, &desc->flags);

	}

	trace_gpio_direction(desc_to_gpio(desc), !value, ret);

	if (ret < 0)