HID: multitouch: fix Elan panels with 2 input modes declaration

bentiss · Jiri Kosina · commit ec6adef5fbc3 · 2018-09-04T21:31:21.000+02:00
When implementing commit 7f81c8d ("HID: multitouch: simplify the settings of the various features"), I wrongly removed a test that made sure we never try to set the second InputMode feature to something else than 0. This broke badly some recent Elan panels that now forget to send the click button in some area of the touchpad. Link: https://bugzilla.kernel.org/show_bug.cgi?id=200899 Fixes: 7f81c8d ("HID: multitouch: simplify the settings of the various features") Cc: stable@vger.kernel.org # v4.18+ Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
@@ -1375,7 +1375,8 @@ static bool mt_need_to_apply_feature(struct hid_device *hdev,
 				     struct hid_usage *usage,
 				     enum latency_mode latency,
 				     bool surface_switch,
-				     bool button_switch)
+				     bool button_switch,
+				     bool *inputmode_found)
 {
 	struct mt_device *td = hid_get_drvdata(hdev);
 	struct mt_class *cls = &td->mtclass;
@@ -1387,6 +1388,14 @@ static bool mt_need_to_apply_feature(struct hid_device *hdev,
 
 	switch (usage->hid) {
 	case HID_DG_INPUTMODE:
+		/*
+		 * Some elan panels wrongly declare 2 input mode features,
+		 * and silently ignore when we set the value in the second
+		 * field. Skip the second feature and hope for the best.
+		 */
+		if (*inputmode_found)
+			return false;
+
 		if (cls->quirks & MT_QUIRK_FORCE_GET_FEATURE) {
 			report_len = hid_report_len(report);
 			buf = hid_alloc_report_buf(report, GFP_KERNEL);
@@ -1402,6 +1411,7 @@ static bool mt_need_to_apply_feature(struct hid_device *hdev,
 		}
 
 		field->value[index] = td->inputmode_value;
+		*inputmode_found = true;
 		return true;
 
 	case HID_DG_CONTACTMAX:
@@ -1439,6 +1449,7 @@ static void mt_set_modes(struct hid_device *hdev, enum latency_mode latency,
 	struct hid_usage *usage;
 	int i, j;
 	bool update_report;
+	bool inputmode_found = false;
 
 	rep_enum = &hdev->report_enum[HID_FEATURE_REPORT];
 	list_for_each_entry(rep, &rep_enum->report_list, list) {
@@ -1457,7 +1468,8 @@ static void mt_set_modes(struct hid_device *hdev, enum latency_mode latency,
 							     usage,
 							     latency,
 							     surface_switch,
-							     button_switch))
+							     button_switch,
+							     &inputmode_found))
 					update_report = true;
 			}
 		}
