linux-kernel - Re: [PATCH] platform/x86: ideapad-laptop: Add sysfs interface for touchpad state

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Message-ID: <1487323140.6980.20.camel@debian.org>
Date:   Fri, 17 Feb 2017 14:49:00 +0530
From:   Ritesh Raj Sarraf <rrs@...ian.org>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Darren Hart <dvhart@...radead.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Ike Panhc <ike.pan@...onical.com>,
        Andy Shevchenko <andy@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] platform/x86: ideapad-laptop: Add sysfs interface for
 touchpad state

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Hash: SHA512

Hello Dmitry,

On Fri, 2017-02-17 at 00:48 -0800, Dmitry Torokhov wrote:
> It looks like the patch is trying to provide a way to disable the
> touchpad when transitioning in tablet mode. 

The keyboard/touchpad get disabled, by hardware, when flipped to tablet mode.
Since currently, the driver has no way to expose a tablet-mode interface, we
relied on this behavior, for the Lenovo Yoga device types.

> In ChromeOS we have a notion
> of "inhibiting" input devices, where userspace policy daemon tells the
> kernel that it is not interested in events from a given device and input
> core will suppress events from such device (and driver may optionally
> put device into low power mode, if it chooses to do so). But in this
> case the control seems to be totally outside of the input driver (which
> I suspect is PS/2 device), so the policy daemon would have to have
> specific knowledge of this new knob.
> 
> BTW, I am not sure if this is actually reliable: if system goes to S3
> with lid open and user changes it into tablet form, nobody will tell the
> EC that touchpad should be ignored and it will wake up the tablet.

I am not sure what you mean here. But:

root@...rner:/sys/bus/platform/devices/VPC2004:00# When in normal mode^C
root@...rner:/sys/bus/platform/devices/VPC2004:00# cat touchpad_mode 
1

S3 Suspend here. THen flip hw to tablet mode. Now, hit power btn to Resume.

root@...rner:/sys/bus/platform/devices/VPC2004:00# Now in tablet mode^C
root@...rner:/sys/bus/platform/devices/VPC2004:00# cat touchpad_mode 
0

- -- 
Ritesh Raj Sarraf | http://people.debian.org/~rrs
Debian - The Universal Operating System
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