Re: [PATCH v2] gpio: convince line to become input in irq helper

[Alexandre Courbot <gnurou@xxxxxxxxx>]

On Thu, Jun 23, 2016 at 6:25 AM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
> The generic IRQ helper library just checks if the IRQ line is
> set as input before activating it for interrupts. As we
> recently started to check things better with .get_dir() it
> turns out that it's good to try to convince the line to become
> an input before attempting to lock it as IRQ.
>
> Cc: Björn Andersson <bjorn.andersson@xxxxxxxxxx>
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> ---
> ChangeLog v1->v2:
> - Propagate the error from .direction_input() so we can rely on
>   it being used.
> ---
>  drivers/gpio/gpiolib.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 5a21a6acf8af..b195ec406ff4 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1505,6 +1505,25 @@ static int gpiochip_irq_reqres(struct irq_data *d)
>         if (!try_module_get(chip->gpiodev->owner))
>                 return -ENODEV;
>
> +       /*
> +        * If it is possible to switch this GPIO to an input
> +        * this is a good time to do it.
> +        */
> +       if (chip->direction_input) {
> +               struct gpio_desc *desc;
> +               int ret;
> +
> +               desc = gpiochip_get_desc(chip, d->hwirq);
> +               if (IS_ERR(desc))
> +                       return PTR_ERR(desc);
> +
> +               ret = chip->direction_input(chip, d->hwirq);
> +               if (ret)
> +                       return ret;
> +
> +               clear_bit(FLAG_IS_OUT, &desc->flags);
> +       }
> +

This looks like a good idea.

Reviewed-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
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