Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit af8dc4d0 authored by Hans de Goede's avatar Hans de Goede Committed by Jiri Kosina
Browse files

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: default avatarHans de Goede <hdegoede@redhat.com>
Reviewed-by: default avatarBenjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent fb55b402

drivers/hid/hid-multitouch.c

+30 −2
Original line number Diff line number Diff line
@@ -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);