linux-kernel - Re: [PATCH v3 3/3] input: gpio-keys: Use hrtimer for software debounce, if possible

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Message-ID: <YFpe6EhydawiMjHB@google.com>
Date:   Tue, 23 Mar 2021 14:34:32 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     od@...c.me, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/3] input: gpio-keys: Use hrtimer for software
 debounce, if possible

On Sun, Mar 07, 2021 at 10:22:40PM +0000, Paul Cercueil wrote:
> We want to be able to report the input event as soon as the debounce
> delay elapsed. However, the current code does not really ensure that,
> as it uses the jiffies-based schedule_delayed_work() API. With a small
> enough HZ value (HZ <= 100), this results in some input events being
> lost, when a key is quickly pressed then released (on a human's time
> scale).
> 
> Switching to hrtimers fixes this issue, and will work even on extremely
> low HZ values (tested at HZ=24). This is however only possible if
> reading the GPIO is possible without sleeping. If this condition is not
> met, the previous approach of using a jiffies-based timer is taken.
> 
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>

Applied with minor edits to make more use of debounce_use_hrtimer flag.

Thanks.

-- 
Dmitry