linux-kernel - Re: [PATCH] gpiolib: fix incorrect IRQ requesting of an active-low lineevent

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Message-ID: <CAMpxmJUzaEREeUxCu2BCV12Huv7K=yeUSKntA5RGMfOQbnxaFg@mail.gmail.com>
Date:   Fri, 5 Jul 2019 11:33:12 +0200
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     Michael Wu <michael.wu@...ics.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio <linux-gpio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, mvp.kutali@...il.com
Subject: Re: [PATCH] gpiolib: fix incorrect IRQ requesting of an active-low lineevent

pt., 5 lip 2019 o 11:30 Michael Wu <michael.wu@...ics.com> napisał(a):
>
> When a pin is active-low, logical trigger edge should be inverted
> to match the same interrupt opportunity.
>
> For example, a button pushed trigger falling edge in ACTIVE_HIGH
> case; in ACTIVE_LOW case, the button pushed trigger rising edge.
> For user space the IRQ requesting doesn't need to do any
> modification except to configuring GPIOHANDLE_REQUEST_ACTIVE_LOW.
>
> Signed-off-by: Michael Wu <michael.wu@...ics.com>
> ---
>  drivers/gpio/gpiolib.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index e013d417a936..b98466a05091 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -956,9 +956,11 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
>         }
>
>         if (eflags & GPIOEVENT_REQUEST_RISING_EDGE)
> -               irqflags |= IRQF_TRIGGER_RISING;
> +               irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
> +                       IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
>         if (eflags & GPIOEVENT_REQUEST_FALLING_EDGE)
> -               irqflags |= IRQF_TRIGGER_FALLING;
> +               irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
> +                       IRQ_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
>         irqflags |= IRQF_ONESHOT;
>
>         INIT_KFIFO(le->events);
> --
> 2.17.1
>

Is this something that causes a bug in user-space? Any scenario to reproduce it?

Bart