[PATCH v2] gpiolib: Preserve desc->flags when setting state

[PATCH v2] gpiolib: Preserve desc->flags when setting state

[Chris Packham]

desc->flags may already have values set by of_gpiochip_add() so make
sure that this isn't undone when setting the initial direction.

Fixes: 3edfb7bd76bd1cba ("gpiolib: Show correct direction from the beginning")
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---

Notes:
    Changes in v2:
    - add braces to avoid ambiguious else warning

 drivers/gpio/gpiolib.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index e013d417a936..5ac57264171b 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1392,12 +1392,13 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 	for (i = 0; i < chip->ngpio; i++) {
 		struct gpio_desc *desc = &gdev->descs[i];
 
-		if (chip->get_direction && gpiochip_line_is_valid(chip, i))
-			desc->flags = !chip->get_direction(chip, i) ?
-					(1 << FLAG_IS_OUT) : 0;
-		else
-			desc->flags = !chip->direction_input ?
-					(1 << FLAG_IS_OUT) : 0;
+		if (chip->get_direction && gpiochip_line_is_valid(chip, i)) {
+			if (!chip->get_direction(chip, i))
+				set_bit(FLAG_IS_OUT, &desc->flags);
+		} else {
+			if (!chip->direction_input)
+				set_bit(FLAG_IS_OUT, &desc->flags);
+		}
 	}
 
 	acpi_gpiochip_add(chip);
-- 
2.22.0

Re: [PATCH v2] gpiolib: Preserve desc->flags when setting state

[Linus Walleij]

Hi Chris,

thanks for your patch!

On Thu, Jul 4, 2019 at 6:21 AM Chris Packham
<chris.packham@alliedtelesis.co.nz> wrote:

> desc->flags may already have values set by of_gpiochip_add() so make
> sure that this isn't undone when setting the initial direction.
>
> Fixes: 3edfb7bd76bd1cba ("gpiolib: Show correct direction from the beginning")
> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> ---
>
> Notes:
>     Changes in v2:
>     - add braces to avoid ambiguious else warning

This is almost the solution!

> -               if (chip->get_direction && gpiochip_line_is_valid(chip, i))
> -                       desc->flags = !chip->get_direction(chip, i) ?
> -                                       (1 << FLAG_IS_OUT) : 0;
> -               else
> -                       desc->flags = !chip->direction_input ?
> -                                       (1 << FLAG_IS_OUT) : 0;
> +               if (chip->get_direction && gpiochip_line_is_valid(chip, i)) {
> +                       if (!chip->get_direction(chip, i))
> +                               set_bit(FLAG_IS_OUT, &desc->flags);

You need to clear_bit() in the reverse case. We just learned we can't
assume anything about the flags here, like just assign them.

> +               } else {
> +                       if (!chip->direction_input)
> +                               set_bit(FLAG_IS_OUT, &desc->flags);

Same here.

Yours,
Linus Walleij