release/5.2.38/HID-wacom-Read-HID_DG_CONTACTMAX-directly-for-non-ge.patch

From cc917378b77eab660ea77fb8abfce36843b7d9ba Mon Sep 17 00:00:00 2001
From: Jason Gerecke <jason.gerecke@wacom.com>
Date: Wed, 1 Apr 2020 14:23:29 -0700
Subject: [PATCH] HID: wacom: Read HID_DG_CONTACTMAX directly for non-generic
 devices

commit 778fbf4179991e7652e97d7f1ca1f657ef828422 upstream.

We've recently switched from extracting the value of HID_DG_CONTACTMAX
at a fixed offset (which may not be correct for all tablets) to
injecting the report into the driver for the generic codepath to handle.
Unfortunately, this change was made for *all* tablets, even those which
aren't generic. Because `wacom_wac_report` ignores reports from non-
generic devices, the contact count never gets initialized. Ultimately
this results in the touch device itself failing to probe, and thus the
loss of touch input.

This commit adds back the fixed-offset extraction for non-generic devices.

Link: https://github.com/linuxwacom/input-wacom/issues/155
Fixes: 184eccd40389 ("HID: wacom: generic: read HID_DG_CONTACTMAX from any feature report")
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Aaron Armstrong Skomra <aaron.skomra@wacom.com>
CC: stable@vger.kernel.org # 5.3+
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
index 602219a8710d..0dbaf68ea291 100644
--- a/drivers/hid/wacom_sys.c
+++ b/drivers/hid/wacom_sys.c
@@ -319,9 +319,11 @@ static void wacom_feature_mapping(struct hid_device *hdev,
 			data[0] = field->report->id;
 			ret = wacom_get_report(hdev, HID_FEATURE_REPORT,
 					       data, n, WAC_CMD_RETRIES);
-			if (ret == n) {
+			if (ret == n && features->type == HID_GENERIC) {
 				ret = hid_report_raw_event(hdev,
 					HID_FEATURE_REPORT, data, n, 0);
+			} else if (ret == 2 && features->type != HID_GENERIC) {
+				features->touch_max = data[1];
 			} else {
 				features->touch_max = 16;
 				hid_warn(hdev, "wacom_feature_mapping: "
-- 
2.7.4