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From: Bartosz Golaszewski <brgl@bgdev.pl>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Hector Bujanda <hector.bujanda@digi.com>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Kent Gibson <warthog618@gmail.com>
Subject: Re: [PATCH] gpiolib: add GPIO_SET_DEBOUNCE_IOCTL
Date: Wed, 29 Apr 2020 14:59:31 +0200	[thread overview]
Message-ID: <CAMRc=MdwSpWkgLTHN+6cOdG7aBAWWYFBC4+tfSNtA2HgX6s_3A@mail.gmail.com> (raw)
In-Reply-To: <CACRpkdaeXFW5K=Npy2ubWsffc7aepEQ5kSJ2HrkrESjaTy_psQ@mail.gmail.com>

śr., 29 kwi 2020 o 14:38 Linus Walleij <linus.walleij@linaro.org> napisał(a):
>
> On Wed, Apr 29, 2020 at 2:06 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> > I understand the need to set debounce time to make line events
> > reliable. As I see it: there'll be a couple steps to add this.
>
> I think there is a serious user-facing problem here though, because
> not all GPIO controllers supports debounce, so the call may return
> "nope" (error code).
>
> I think that is unavoidable with things like pull-up/down or drive
> strength, but for debounce I think we could do better.

For bias we don't return an error if the operation is not supported by
the driver.

> drivers/input/keyboard/gpio_keys.c contains generic
> debounce code using kernel timers if the GPIO driver
> cannot provide debouncing, and I have thought for a long
> time that it would be nice if we could do this generic, so that
> we always provide debouncing if requested, even for in-kernel
> consumers but most certainly for userspace consumers,
> else userspace will just start to reinvent this too.
>

Thanks for bringing this to my attention. This definitely looks like
something we could pull into gpiolib for others to use.

Bart

  reply	other threads:[~2020-04-29 12:59 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-19  0:18 [PATCH] gpiolib: add GPIO_SET_DEBOUNCE_IOCTL Hector Bujanda
2020-04-29 12:06 ` Bartosz Golaszewski
2020-04-29 12:38   ` Linus Walleij
2020-04-29 12:59     ` Bartosz Golaszewski [this message]
2020-04-30 13:32       ` Bujanda, Hector
2020-04-30 14:58         ` Kent Gibson
2020-05-04 10:31           ` Bartosz Golaszewski
2020-05-07  3:39             ` Kent Gibson
2020-05-14 14:21               ` Linus Walleij
2020-05-12 17:55             ` Linus Walleij
2020-05-13  4:33               ` Kent Gibson
2020-05-25  2:22     ` Kent Gibson
2020-05-25 12:17       ` Linus Walleij
2020-05-25 15:17         ` Kent Gibson
2020-05-27  5:31           ` Linus Walleij
2020-05-04 12:37   ` Andy Shevchenko
2020-04-19  0:22 Hector Bujanda
2020-04-28 10:35 ` Linus Walleij
2020-04-29  1:49   ` Kent Gibson

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