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HID: wacom: Tie cached HID_DG_CONTACTCOUNT indices to report ID 

The cached indicies 'cc_index' and 'cc_value_index' introduced in 1b5d514
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>
This commit is contained in:
Jason Gerecke 2015-10-07 16:54:21 -07:00 committed by Jiri Kosina
parent e8e8843800
commit 499522c8c0
2 changed files with 27 additions and 0 deletions
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26
drivers/hid/wacom_wac.c
View File

@ -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];

1
drivers/hid/wacom_wac.h
View File

@ -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;