The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e735244e2cf068f98b6384681a38993e0517a838 Mon Sep 17 00:00:00 2001

From: Bartosz Golaszewski bgolaszewski@baylibre.com Date: Tue, 1 Oct 2019 11:44:53 +0200 Subject: [PATCH] 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: 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

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index bdbc1649eafa..5833e4f380d6 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -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)