linux-kernel - Re: [rfd] saving old mice -- button glitching/debouncing

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Message-ID: <20181215102902.GA8022@amd>
Date:   Sat, 15 Dec 2018 11:29:02 +0100
From:   Pavel Machek <pavel@....cz>
To:     Vojtech Pavlik <vojtech@...e.cz>
Cc:     kernel list <linux-kernel@...r.kernel.org>, jikos@...e.cz,
        linux-input@...r.kernel.org, dmitry.torokhov@...il.com
Subject: Re: [rfd] saving old mice -- button glitching/debouncing

On Sat 2018-12-15 11:12:21, Vojtech Pavlik wrote:
> On Sat, Dec 15, 2018 at 10:47:22AM +0100, Pavel Machek wrote:
> 
> > > > b) would it be acceptable if done properly? (cmd line option to
> > > > enable, avoiding duplicate/wrong events?)
> > > 
> > > Well, for one, you shouldn't be using a timer, all the debouncing can be
> > > done by math on the event timestamps.
> > 
> > Not... really, right? You need to send an release some time after
> > button indicates release if bounce did not happen. It is similar to
> > autorepeat needing a timer.
> 
> You can send the first release and ignore all presses and releases in a
> time window after that.

I could, and it would work for glitches on release, but that would do
very bad things if switch glitched on press, right?

"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XX           " ->
"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX              " ... ok

"XX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX..." ->
"XX                                  ..." ... bad idea. [Maybe could be
detected with "XX " being unusually short?]

But I believe I see 

"XXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXX" on X220 device, too.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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