On Tue, Nov 23, 2010 at 12:48:07PM -0800, Ping Cheng wrote:

Hi all,

I am not going to write a patch for this request before I get the
permission for the new tool type. It affects all touch screen devices
(under drivers/input/touchscreen) that support both pen and touch.

Right now, in the user land, BTN_TOUCH is used to indicate a single
touch events. BTN_TOUCH and !BTN_TOOL_PEN
(http://udev.sourcearchive.com/documentation/161-1/input__id_8c-source.html)
are used to determine if the device is a touch screen device or not a
pen. With both pen and touch on the same logical port (serial touch
screen with pen and touch enabled, refer to wacom_w8001.c), BTN_TOUCH
and !BTN_TOOL_PEN will always be false, which indicates a
non-touchscreen device. That is wrong.

Unless we have other means to tell the user land a device is a
touchscreen, BTN_TOUCH with !BTN_TOOL_PEN won't do the job for us.

I've already had a value for the new type:

+#define BTN_TOOL_TOUCH       0x149

This new type resolves the confusion we had for the existing serial
pen and touch enabled touchscreen devices. Considering we are merging
the two logical ports for USB devices, the new type is required for
the future USB touchscreen support as well.

How is BTN_TOOL_TOUCH is different from BTN_TOOL_FINGER?

-- 
Dmitry