linux-kernel - Re: Spurious touchpad events with closed LID

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Date:   Wed, 28 Jun 2017 22:15:30 +0200
From:   Pavel Machek <pavel@....cz>
To:     Pali Rohár <pali.rohar@...il.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-kernel@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: Spurious touchpad events with closed LID

Hi!

> > > When I'm using dock with external input devices (keyboard + mouse)
> > > and LID is closed, I'm getting spurious touchpad events and random
> > > mouse clicks and movements.
> > > 
> > > It is because top part of LID is above touchpad and probably
> > > generates touch pushes.
> > > 
> > > Year (or two?) when I had conversation with ALPS people I was told
> > > that Windows driver is automatically turning touchpad off when
> > > ACPI LID close event is received (and similarly turn touchpad on).
> > > 
> > > Maybe Linux should do similar thing? Random movement or touchpad
> > > clicks is really annoying. But I'm not sure if kernel or userspace
> > > should do this job... What do you think?
> > 
> > It is a matter of policy (deciding when device is "usable") and this
> > should be controlled from userspace. Kernel should provide necessary
> > knobs for it though. For a long time I was saying that it should be
> > done at device core level, but I do not think we will ever get
> > there.
> > 
> > On ChromeOS input devices export "inhibit" attribute that basically
> > overrides open/close count and prevents delivery of events to
> > userspace, and power management driver controls this attribute
> > together with wake up and others.
> 
> Hm... this sounds like a "disable" property for each event device which 
> I was talking about months ago (ccing Pavel). Very similar problem is on 
> Nokia N900, where touchscreen needs to be turned off when screen is 
> locked and phone in pocket.

Yes, disable property would be nice.

> > This allows us to implement
> > policies like "the touchpad should only be active and a wakeup
> > source while the device is in laptop mode, but not in tablet or tent
> > mode, or when lid is closed", "disable keyboard in tablet mode or
> > when list is closed", etc.

While policy normally belongs to userspace, I'd argue this is
workaround for a hardware bug, and in-kernel solution would be
acceptable.

Anyway, disable attribute would be nice first step.

Best regards,
									Pavel

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

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