Re: [PATCH] gpiolib: don't clear FLAG_IS_OUT when emulating open-drain/open-source

wt., 10 wrz 2019 o 10:22 Bartosz Golaszewski brgl@bgdev.pl napisał(a):

From: Bartosz Golaszewski bgolaszewski@baylibre.com

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@vger.kernel.org Reported-by: Kent Gibson warthog618@gmail.com Signed-off-by: Bartosz Golaszewski bgolaszewski@baylibre.com

---

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