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Re: [PATCH] Input: synaptics-rmi4 - Report slot as inactive when contact is a palm

On 03/16/2017 05:04 PM, Dmitry Torokhov wrote:
On Thu, Mar 16, 2017 at 04:56:31PM -0700, Andrew Duggan wrote:
When the firmware identifies a contact as a palm the driver sets the tool
type to MT_TOOL_PALM, but sets the slot state as active. Reporting the
palm as active results in userspace input libraries considering the palm
as a valid contact. Touchpads which previously were using hid-multitouch
are now not suppressing palms when switching to the RMI4 driver. This
change fixes palm rejection when using the RMI4 driver.

Signed-off-by: Andrew Duggan <aduggan@xxxxxxxxxxxxx>
Tested-by: Cameron Gutman <aicommander@xxxxxxxxx>
  drivers/input/rmi4/rmi_2d_sensor.c | 3 ++-
  1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/input/rmi4/rmi_2d_sensor.c b/drivers/input/rmi4/rmi_2d_sensor.c
index 8bb866c..8d1f295 100644
--- a/drivers/input/rmi4/rmi_2d_sensor.c
+++ b/drivers/input/rmi4/rmi_2d_sensor.c
@@ -80,7 +80,8 @@ void rmi_2d_sensor_abs_report(struct rmi_2d_sensor *sensor,
  		input_mt_slot(input, slot);
input_mt_report_slot_state(input, obj->mt_tool,
-				   obj->type != RMI_2D_OBJECT_NONE);
+				   (obj->type != RMI_2D_OBJECT_NONE)
+				   && (obj->type != RMI_2D_OBJECT_PALM));
if (obj->type != RMI_2D_OBJECT_NONE) {
  		obj->x = sensor->tracking_pos[slot].x;
If we are relying on hardware to do palm rejection, then we should not
be reporting the rest of the events for palm either (i.e. the condition
in the if statement above should also be updated).

But I do not understand why userspace doe snot do the right thing? Yes,
the slot is active, but reported contact type is MT_TOOL_PALM, so it
knows what it deals with.


My intent is to notify userspace that there is a palm present. But, if userspace does not have code which explicitly handles the MT_TOOL_PALM type it won't be considered a finger. I think it is only recently that drivers have started reporting MT_TOOL_PALM to userspace so I'm not sure if libraries like libinput make use of it yet.

Starting with v4.11 some touchpads will be switching from hid-multitouch to the RMI4 driver and reporting palms as active results in unsuppressed palms. I want to avoid users from upgrading and experiencing a degradation in usability. In which case I can update the if statement and resubmit. This is basically how hid-multitouch is handling it. Maybe in the future we can add a parameter to enable reporting palms to userspace.