wt., 10 wrz 2019 o 10:22 Bartosz Golaszewski <brgl@xxxxxxxx> napisał(a):
>
> From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
>
> 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: c663e5f56737 ("gpio: support native single-ended hardware drivers")
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Kent Gibson <warthog618@xxxxxxxxx>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> ---
> drivers/gpio/gpiolib.c | 27 +++++++++++++++++++--------
> 1 file changed, 19 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index cca749010cd0..6bb4191d3844 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -2769,8 +2769,10 @@ 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),
> @@ -2778,8 +2780,10 @@ 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);
> @@ -2787,6 +2791,17 @@ 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);
>
> @@ -3147,8 +3162,6 @@ static void gpio_set_open_drain_value_commit(struct gpio_desc *desc, bool value)
>
> if (value) {
> err = chip->direction_input(chip, offset);
> - if (!err)
> - clear_bit(FLAG_IS_OUT, &desc->flags);
> } else {
> err = chip->direction_output(chip, offset, 0);
> if (!err)
> @@ -3178,8 +3191,6 @@ static void gpio_set_open_source_value_commit(struct gpio_desc *desc, bool value
> set_bit(FLAG_IS_OUT, &desc->flags);
> } else {
> err = chip->direction_input(chip, offset);
> - if (!err)
> - clear_bit(FLAG_IS_OUT, &desc->flags);
> }
> trace_gpio_direction(desc_to_gpio(desc), !value, err);
> if (err < 0)
> --
> 2.21.0
>
Queued for fixes.
Bart
