Re: [PATCH] Input: Document the device properties

[Jussi Pakkanen <jussi.pakkanen@canonical.com>]

On 01/30/2012 10:35 AM, Henrik Rydberg wrote:

> +INPUT_PROP_BUTTONPAD:
> +--------------------
> +For touchpads where the button is placed under the touchpad, such as
> +clickpads and macbooks, this property should be set. Common in devices from
> +2009 and onwards.

"Under" can be interpreted to mean "under as in towards the user when 
looking from above" as well as "under as in towards the Earth's core". A 
more unambiguous description would be something like "For touchpads 
where a physical button is beneath the pad's touch surface so that 
pushing down on the touchpad causes a button click".

> +INPUT_PROP_SEMI_MT:
> +------------------
> +Some touchpads, most common between 2008 and 2011, can detect the presence
> +of multiple contacts without resolving the individual positions; only the
> +number of contacts and the corresponding bounding box is known. For such
> +touchpads, the semi-mt property should be set.

A "corresponding bounding box" usually means "a bounding box that 
contains all touches on the touchpad". I've been told (though I have not 
checked it myself) that there are devices that don't do this. They only 
report a bounding box for some subset of touches. If this is the case, 
it should be documented here.