From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
[ Upstream commit e735244e2cf068f98b6384681a38993e0517a838 ]
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>
[Bartosz: backported to v5.3, v4.19]
Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 3289b53a7ba14..565ab945698ca 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2649,8 +2649,10 @@ 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_drive_single_ended(gc, gpio_chip_hwgpio(desc),
@@ -2658,8 +2660,10 @@ 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_drive_single_ended(gc, gpio_chip_hwgpio(desc),
PIN_CONFIG_DRIVE_PUSH_PULL);
@@ -2667,6 +2671,17 @@ 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);
@@ -2980,8 +2995,6 @@ 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)
@@ -3011,8 +3024,6 @@ 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)
--
2.20.1
