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

[Ritesh Raj Sarraf <rrs@debian.org>]

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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@learner:/sys/bus/platform/devices/VPC2004:00# When in normal mode^C
root@learner:/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@learner:/sys/bus/platform/devices/VPC2004:00# Now in tablet mode^C
root@learner:/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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