HID: wacom: Tie cached HID_DG_CONTACTCOUNT indices to report ID (499522c8) · Commits · 戴 / test

The cached indicies 'cc_index' and 'cc_value_index' introduced in 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:

Jason Gerecke <jason.gerecke@wacom.com> Signed-off-by:

Jiri Kosina <jkosina@suse.cz>

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;

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