[PATCH 4.14 030/109] HID: multitouch: Only look at non touch fields in first packet of a frame

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hans de Goede <hdego...@redhat.com>


[ Upstream commit 55746d28d66860bccaae20a67b55b9d5db7c14af ]

Devices in "single finger hybrid mode" will send one report per finger,
on some devices only the first report of such a multi-packet frame will
contain a value for BTN_LEFT, in subsequent reports (if multiple fingers
are down) the value is always 0, causing hid-mt to report BTN_LEFT going
1 - 0 - 1 - 0 when pressing a clickpad and putting down a second finger.
This happens for example on USB 0603:0002 mt touchpads.

This commit fixes this by only reporting non touch fields for the first
packet of a (possibly) multi-packet frame.

Signed-off-by: Hans de Goede <hdego...@redhat.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoi...@redhat.com>
Signed-off-by: Jiri Kosina <jkos...@suse.cz>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/hid/hid-multitouch.c |   17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -738,9 +738,11 @@ static int mt_touch_event(struct hid_dev
 }
 
 static void mt_process_mt_event(struct hid_device *hid, struct hid_field 
*field,
-                               struct hid_usage *usage, __s32 value)
+                               struct hid_usage *usage, __s32 value,
+                               bool first_packet)
 {
        struct mt_device *td = hid_get_drvdata(hid);
+       __s32 cls = td->mtclass.name;
        __s32 quirks = td->mtclass.quirks;
        struct input_dev *input = field->hidinput->input;
 
@@ -794,6 +796,15 @@ static void mt_process_mt_event(struct h
                        break;
 
                default:
+                       /*
+                        * For Win8 PTP touchpads we should only look at
+                        * non finger/touch events in the first_packet of
+                        * a (possible) multi-packet frame.
+                        */
+                       if ((cls == MT_CLS_WIN_8 || cls == MT_CLS_WIN_8_DUAL) &&
+                           !first_packet)
+                               return;
+
                        if (usage->type)
                                input_event(input, usage->type, usage->code,
                                                value);
@@ -813,6 +824,7 @@ static void mt_touch_report(struct hid_d
 {
        struct mt_device *td = hid_get_drvdata(hid);
        struct hid_field *field;
+       bool first_packet;
        unsigned count;
        int r, n;
 
@@ -831,6 +843,7 @@ static void mt_touch_report(struct hid_d
                        td->num_expected = value;
        }
 
+       first_packet = td->num_received == 0;
        for (r = 0; r < report->maxfield; r++) {
                field = report->field[r];
                count = field->report_count;
@@ -840,7 +853,7 @@ static void mt_touch_report(struct hid_d
 
                for (n = 0; n < count; n++)
                        mt_process_mt_event(hid, field, &field->usage[n],
-                                       field->value[n]);
+                                           field->value[n], first_packet);
        }
 
        if (td->num_received >= td->num_expected)