Re: [External] Using IIO to export laptop palm-sensor and lap-mode info to userspace?

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 10/7/20 1:35 PM, Bastien Nocera wrote:
> On Wed, 2020-10-07 at 11:51 +0200, Hans de Goede wrote:
>> <snip>
>>> Dmitry, any existing stuff like this in input?
>>
>> There already is a SW_FRONT_PROXIMITY defined in
>> input-event-codes.h, which I guess means detection if
>> someone is sitting in front of the screen. So we could add:
>>
>> SW_LAP_PROXIMITY
>> SW_PALMREST_PROXIMITY,
>>
>> And then we have a pretty decent API for this I think.
> 
>  From the point of view of writing the consumer code for this API, it's
> rather a lot of pain to open the device node (hoping that it's the
> right one for what we need), getting the initial state, setting up
> masks to avoid being woken up for every little event, and parsing those
> events.

There is not much difference with the iio sysfs API though, you would
also need to iterate over all the iio devices and test if they
are a proximity sensor (and read the new location sysfs file discussed).

> Where would the necessary bits of metadata for daemons to be able to
> find that those switches need to get added?

evdev files export info on which events they can report. Not only
the types of events (EV_SW in this case) but also a bitmask for
which event-codes they can report within that type.

> If you go down that route, you'll definitely want a want to attach the
> "palmrest" to the touchpad/keyboard that it corresponds to, otherwise
> that might have weird interactions when using external keyboards and
> touchpads. (I don't know what you'd use that proximity sensor for
> though)

The proximity sensor is primarily for deciding how strong a signal
wireless devices inside the laptop may emit.

Regards,

Hans