Re: [PATCH 03/12] Input: synaptics - fix minimum reported ABS_TOOL_WIDTH

Jeffrey Brown
2011-07-09T06:24:52Z

On Tue, Jun 28, 2011 at 10:07 PM, <djkurtz@chromium.org> wrote:
> From: Daniel Kurtz <djkurtz@chromium.org>
>
> Synaptics touchpads report a 'w' value in each data report.
> For touchpads that support palm detection, when there is a single finger
> on the pad, the 'w' value reports its width in the range 4 to 15.
> Thus, the minimum valid width is 4.
>
> Note: Other values of 'w' are used to report special conditions:
>  w=0: 2 fingers are on the pad
>  w=1: 3 or more fingers are on the pad
>  w=2: the packet contains "Advanced Gesture Mode" data.

Ideally we should scale this to a physically meaningful quantity
instead, such as surface units. That would require knowing the
distance between each capacitive touch channel and then scaling W - 4
by that amount before reporting it.

These values are all kind of mysterious to user-space anyways unless
the physical nature of the device is known by other means (such as
configuration files).

Jeff.