On Tue, Jun 28, 2011 at 10:07 PM,  [off-list ref] wrote:

From: Daniel Kurtz <redacted>

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.
--
To unsubscribe from this list: send the line "unsubscribe linux-input" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html