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

[ Upstream commit e735244e2c ]

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: c663e5f567 ("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>
[Bartosz: backported to v4.14]
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Bartosz Golaszewski 2019-10-14 18:10:24 +02:00 committed by Greg Kroah-Hartman
parent 7b23f5f6cc
commit a77def3a06
1 changed files with 19 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
drivers/gpio/gpiolib.c
View File

@ -2329,8 +2329,10 @@ static int _gpiod_direction_output_raw(struct gpio_desc *desc, int value)
if (!ret)
goto set_output_value;
/* Emulate open drain by not actively driving the line high */
if (val)
return gpiod_direction_input(desc);
if (val) {
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),
@ -2338,8 +2340,10 @@ static int _gpiod_direction_output_raw(struct gpio_desc *desc, int value)
if (!ret)
goto set_output_value;
/* Emulate open source by not actively driving the line low */
if (!val)
return gpiod_direction_input(desc);
if (!val) {
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);
@ -2359,6 +2363,17 @@ set_output_value:
trace_gpio_value(desc_to_gpio(desc), 0, val);
trace_gpio_direction(desc_to_gpio(desc), 0, ret);
return ret;
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;
}
/**
@ -2540,8 +2555,6 @@ static void _gpio_set_open_drain_value(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)
@ -2571,8 +2584,6 @@ static void _gpio_set_open_source_value(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)