4.3-stable review patch. If anyone has any objections, please let me know.
------------------ From: Jason Gerecke <[email protected]> commit 499522c8c015de995aabce3d0f0bf4b9b17f44c3 upstream. 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). Signed-off-by: Jason Gerecke <[email protected]> Signed-off-by: Jiri Kosina <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/hid/wacom_wac.c | 26 ++++++++++++++++++++++++++ drivers/hid/wacom_wac.h | 1 + 2 files changed, 27 insertions(+) --- a/drivers/hid/wacom_wac.c +++ b/drivers/hid/wacom_wac.c @@ -1628,6 +1628,7 @@ static void wacom_wac_finger_usage_mappi 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 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]; --- a/drivers/hid/wacom_wac.h +++ b/drivers/hid/wacom_wac.h @@ -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;
