HID: multitouch: Add quirk for VTL touch panels

VTL panels do not switch to the multitouch mode until the input mode
feature is read by the host. This should normally be done by
usbhid, but it looks like an other bug prevents usbhid to properly
retrieve the feature state. As a workaround, we force the reading of
the feature in mt_set_input_mode for such devices.
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Mathieu Magnaudet <mathieu.magnaudet@enac.fr>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-ids.h

@@ -931,6 +931,9 @@
 #define USB_DEVICE_ID_VERNIER_CYCLOPS	0x0004
 #define USB_DEVICE_ID_VERNIER_LCSPEC	0x0006
 
+#define USB_VENDOR_ID_VTL		0x0306
+#define USB_DEVICE_ID_VTL_MULTITOUCH_FF3F	0xff3f
+
 #define USB_VENDOR_ID_WACOM		0x056a
 #define USB_DEVICE_ID_WACOM_GRAPHIRE_BLUETOOTH	0x81
 #define USB_DEVICE_ID_WACOM_INTUOS4_BLUETOOTH   0x00BD

drivers/hid/hid-multitouch.c

@@ -67,6 +67,7 @@ MODULE_LICENSE("GPL");
 #define MT_QUIRK_IGNORE_DUPLICATES	(1 << 10)
 #define MT_QUIRK_HOVERING		(1 << 11)
 #define MT_QUIRK_CONTACT_CNT_ACCURATE	(1 << 12)
+#define MT_QUIRK_FORCE_GET_FEATURE	(1 << 13)
 
 #define MT_INPUTMODE_TOUCHSCREEN	0x02
 #define MT_INPUTMODE_TOUCHPAD		0x03
@@ -150,6 +151,7 @@ static void mt_post_parse(struct mt_device *td);
 #define MT_CLS_FLATFROG				0x0107
 #define MT_CLS_GENERALTOUCH_TWOFINGERS		0x0108
 #define MT_CLS_GENERALTOUCH_PWT_TENFINGERS	0x0109
+#define MT_CLS_VTL				0x0110
 
 #define MT_DEFAULT_MAXCONTACT	10
 #define MT_MAX_MAXCONTACT	250
@@ -255,6 +257,11 @@ static struct mt_class mt_classes[] = {
 		.sn_move = 2048,
 		.maxcontacts = 40,
 	},
+	{ .name = MT_CLS_VTL,
+		.quirks = MT_QUIRK_ALWAYS_VALID |
+			MT_QUIRK_CONTACT_CNT_ACCURATE |
+			MT_QUIRK_FORCE_GET_FEATURE,
+	},
 	{ }
 };
 
@@ -809,6 +816,9 @@ static void mt_set_input_mode(struct hid_device *hdev)
 	struct mt_device *td = hid_get_drvdata(hdev);
 	struct hid_report *r;
 	struct hid_report_enum *re;
+	struct mt_class *cls = &td->mtclass;
+	char *buf;
+	int report_len;
 
 	if (td->inputmode < 0)
 		return;
@@ -816,6 +826,18 @@ static void mt_set_input_mode(struct hid_device *hdev)
 	re = &(hdev->report_enum[HID_FEATURE_REPORT]);
 	r = re->report_id_hash[td->inputmode];
 	if (r) {
+		if (cls->quirks & MT_QUIRK_FORCE_GET_FEATURE) {
+			report_len = ((r->size - 1) >> 3) + 1 + (r->id > 0);
+			buf = hid_alloc_report_buf(r, GFP_KERNEL);
+			if (!buf) {
+				hid_err(hdev, "failed to allocate buffer for report\n");
+				return;
+			}
+			hid_hw_raw_request(hdev, r->id, buf, report_len,
+					   HID_FEATURE_REPORT,
+					   HID_REQ_GET_REPORT);
+			kfree(buf);
+		}
 		r->field[0]->value[td->inputmode_index] = td->inputmode_value;
 		hid_hw_request(hdev, r, HID_REQ_SET_REPORT);
 	}
@@ -1281,6 +1303,11 @@ static const struct hid_device_id mt_devices[] = {
 		MT_USB_DEVICE(USB_VENDOR_ID_UNITEC,
 			USB_DEVICE_ID_UNITEC_USB_TOUCH_0A19) },
 
+	/* VTL panels */
+	{ .driver_data = MT_CLS_VTL,
+		MT_USB_DEVICE(USB_VENDOR_ID_VTL,
+			USB_DEVICE_ID_VTL_MULTITOUCH_FF3F) },
+
 	/* Wistron panels */
 	{ .driver_data = MT_CLS_NSMU,
 		MT_USB_DEVICE(USB_VENDOR_ID_WISTRON,