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From f5c1da991de077420fda17a236342de5a0068f5d Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede@redhat.com>
Date: Wed, 22 Nov 2017 12:57:08 +0100
Subject: [PATCH v2 1/3] HID: multitouch: Properly deal with Win8 PTP reports
with 0 touches
The Windows Precision Touchpad spec "Figure 4 Button Only Down and Up"
and "Table 9 Report Sequence for Button Only Down and Up" indicate
that the first packet of a (possibly hybrid mode multi-packet) frame
may contain a contact-count of 0 if only a button is pressed and no
fingers are detected.
This means that a value of 0 for contact-count is a valid value and
should be used as expected contact count when it is the first packet
(num_received == 0), as extra check to make sure that this is the first
packet of a buttons only frame, we also check that the timestamp is
different.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---
drivers/hid/hid-multitouch.c | 32 ++++++++++++++++++++++++++++++--
1 file changed, 30 insertions(+), 2 deletions(-)
diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 9ef24b518f12..d8b1cad74faf 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -119,6 +119,9 @@ struct mt_device {
unsigned long mt_io_flags; /* mt flags (MT_IO_FLAGS_*) */
int cc_index; /* contact count field index in the report */
int cc_value_index; /* contact count value index in the field */
+ int scantime_index; /* scantime field index in the report */
+ int scantime_val_index; /* scantime value index in the field */
+ int prev_scantime; /* scantime reported in the previous packet */
unsigned last_slot_field; /* the last field of a slot */
unsigned mt_report_id; /* the report ID of the multitouch device */
unsigned long initial_quirks; /* initial quirks state */
@@ -599,6 +602,12 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
EV_MSC, MSC_TIMESTAMP);
input_set_capability(hi->input, EV_MSC, MSC_TIMESTAMP);
mt_store_field(usage, td, hi);
+ /* Ignore if indexes are out of bounds. */
+ if (field->index >= field->report->maxfield ||
+ usage->usage_index >= field->report_count)
+ return 1;
+ td->scantime_index = field->index;
+ td->scantime_val_index = usage->usage_index;
return 1;
case HID_DG_CONTACTCOUNT:
/* Ignore if indexes are out of bounds. */
@@ -855,9 +864,10 @@ static void mt_process_mt_event(struct hid_device *hid, struct hid_field *field,
static void mt_touch_report(struct hid_device *hid, struct hid_report *report)
{
struct mt_device *td = hid_get_drvdata(hid);
+ __s32 cls = td->mtclass.name;
struct hid_field *field;
unsigned count;
- int r, n;
+ int r, n, scantime = 0;
/* sticky fingers release in progress, abort */
if (test_and_set_bit(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))
@@ -867,12 +877,29 @@ static void mt_touch_report(struct hid_device *hid, struct hid_report *report)
* Includes multi-packet support where subsequent
* packets are sent with zero contactcount.
*/
+ if (td->scantime_index >= 0) {
+ field = report->field[td->scantime_index];
+ scantime = field->value[td->scantime_val_index];
+ }
if (td->cc_index >= 0) {
struct hid_field *field = report->field[td->cc_index];
int value = field->value[td->cc_value_index];
- if (value)
+
+ /*
+ * For Win8 PTPs the first packet (td->num_received == 0) may
+ * have a contactcount of 0 if there only is a button event.
+ * We double check that this is not a continuation packet
+ * of a possible multi-packet frame be checking that the
+ * timestamp has changed.
+ */
+ if ((cls == MT_CLS_WIN_8 || cls == MT_CLS_WIN_8_DUAL) &&
+ td->num_received == 0 && td->prev_scantime != scantime)
+ td->num_expected = value;
+ /* A non 0 contact count always indicates a first packet */
+ else if (value)
td->num_expected = value;
}
+ td->prev_scantime = scantime;
for (r = 0; r < report->maxfield; r++) {
field = report->field[r];
@@ -1329,6 +1356,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
td->maxcontact_report_id = -1;
td->inputmode_value = MT_INPUTMODE_TOUCHSCREEN;
td->cc_index = -1;
+ td->scantime_index = -1;
td->mt_report_id = -1;
hid_set_drvdata(hdev, td);
--
2.14.3
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