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Commit 499522c8 authored by Jason Gerecke's avatar Jason Gerecke Committed by Jiri Kosina
Browse files

HID: wacom: Tie cached HID_DG_CONTACTCOUNT indices to report ID 



The cached indicies 'cc_index' and 'cc_value_index' introduced in 1b5d514a
are only valid for a single report ID. If a touchscreen has multiple
reports with a HID_DG_CONTACTCOUNT usage, its possible that the values
will not be correct for the report we're handling, resulting in an
incorrect value for 'num_expected'. This has been observed with the Cintiq
Companion 2.

To address this, we store the ID of the report those indicies are valid
for in a new  'cc_report' variable. Before using them to get the expected
contact count, we first check if the ID of the report we're processing
matches 'cc_report'. If it doesn't, we update the indicies to point to
the HID_DG_CONTACTCOUNT usage of the current report (if it has one).

Cc: stable@vger.kernel.org
Signed-off-by: default avatarJason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent e8e88438

drivers/hid/wacom_wac.c

+26 −0
Original line number Diff line number Diff line
@@ -1628,6 +1628,7 @@ static void wacom_wac_finger_usage_mapping(struct hid_device *hdev, 
		wacom_map_usage(input, usage, field, EV_KEY, BTN_TOUCH, 0);

		break;

	case HID_DG_CONTACTCOUNT:

		wacom_wac->hid_data.cc_report = field->report->id;

		wacom_wac->hid_data.cc_index = field->index;

		wacom_wac->hid_data.cc_value_index = usage->usage_index;

		break;
@@ -1715,6 +1716,31 @@ static void wacom_wac_finger_pre_report(struct hid_device *hdev, 
	struct wacom_wac *wacom_wac = &wacom->wacom_wac;

	struct hid_data* hid_data = &wacom_wac->hid_data;



	if (hid_data->cc_report != 0 &&

	    hid_data->cc_report != report->id) {

		int i;



		hid_data->cc_report = report->id;

		hid_data->cc_index = -1;

		hid_data->cc_value_index = -1;



		for (i = 0; i < report->maxfield; i++) {

			struct hid_field *field = report->field[i];

			int j;



			for (j = 0; j < field->maxusage; j++) {

				if (field->usage[j].hid == HID_DG_CONTACTCOUNT) {

					hid_data->cc_index = i;

					hid_data->cc_value_index = j;



					/* break */

					i = report->maxfield;

					j = field->maxusage;

				}

			}

		}

	}



	if (hid_data->cc_index >= 0) {

		struct hid_field *field = report->field[hid_data->cc_index];

		int value = field->value[hid_data->cc_value_index];

drivers/hid/wacom_wac.h

+1 −0
Original line number Diff line number Diff line
@@ -198,6 +198,7 @@ struct hid_data { 
	int width;

	int height;

	int id;

	int cc_report;

	int cc_index;

	int cc_value_index;

	int num_expected;