Re: [PATCH 4/4] Input: Synaptics: Add INPUT_PROP_SYNAPTICS_T3R2 property

On 06/10/11 17:13, Henrik Rydberg wrote:

On Fri, Jun 10, 2011 at 03:55:04PM -0400, Derek Foreman wrote:

quoted

This new property indicates that the trackpad is able to track more than two contacts, but can only report the positions of two contacts due to bus bandwidth limitations.

Signed-off-by: Derek Foreman<redacted>
---
  drivers/input/mouse/synaptics.c |    3 +++
  include/linux/input.h           |    1 +
  2 files changed, 4 insertions(+), 0 deletions(-)

This information is already contained in INPUT_PROP_SEMI_MT, together
with the use of BTN_TRIPLETAP. Please check
Documentation/input/event-codes.txt for further details.

I really sorry, but I don't understand how this provides the same information.

INPUT_PROP_SEMI_MT, at least according to input.h specifies that the device reports a rectangle only, and not accurate touch co-ordinates.

BTN_TOOL_TRIPLETAP indicates that there are 3 fingers on the pad.


My intent was to indicate to userspace that the device is reporting co-ordinates like certain synaptics devices do:

3 fingers are accurately tracked
2 fingers are accurately (not bounding box) reported

Further, all the idiosyncrasies of the synaptics method of reporting apply:
The device has 3 "slots" for tracking data, and once they are all filled, it reports slots 1 and 3.  If the slot 1 contact is lifted, slots 2 and 3 will report.  If a third finger is once again added to the pad, it will become the new slot 1.

INPUT_PROP_SEMI_MT is actually inaccurate for these devices, and in retrospect, the bounding box patch should have removed that bit from the properties of the devices it applies to.