From af8dc4d0949092c4fba17ebb9e54448697c3d4e0 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Wed, 22 Nov 2017 12:57:08 +0100 Subject: [PATCH] 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 Reviewed-by: Benjamin Tissoires Signed-off-by: Jiri Kosina --- 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 9ef24b5..d8b1cad 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); -- 2.7.4