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Date: Wed, 29 Apr 2020 14:38:13 +0200 From: Linus Walleij <linus.walleij@...aro.org> To: Bartosz Golaszewski <brgl@...ev.pl> Cc: Hector Bujanda <hector.bujanda@...i.com>, "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Kent Gibson <warthog618@...il.com> Subject: Re: [PATCH] gpiolib: add GPIO_SET_DEBOUNCE_IOCTL On Wed, Apr 29, 2020 at 2:06 PM Bartosz Golaszewski <brgl@...ev.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. 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. Yours, Linus Walleij
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