From 286f3f478796fb4f9e003e9f7d649f3c33f08d2f Mon Sep 17 00:00:00 2001
From: Jason Gerecke <killertofu@gmail.com>
Date: Thu, 13 Apr 2017 08:39:49 -0700
Subject: HID: wacom: Treat HID_DG_TOOLSERIALNUMBER as unsigned

Because HID_DG_TOOLSERIALNUMBER doesn't first cast the value recieved from HID
to an unsigned type, sign-extension rules can cause the value of
wacom_wac->serial[0] to inadvertently wind up with all 32 of its highest bits
set if the highest bit of "value" was set.

This can cause problems for Tablet PC devices which use AES sensors and the
xf86-input-wacom userspace driver. It is not uncommon for AES sensors to send a
serial number of '0' while the pen is entering or leaving proximity. The
xf86-input-wacom driver ignores events with a serial number of '0' since it
cannot match them up to an in-use tool.  To ensure the xf86-input-wacom driver
does not ignore the final out-of-proximity event, the kernel does not send
MSC_SERIAL events when the value of wacom_wac->serial[0] is '0'. If the highest
bit of HID_DG_TOOLSERIALNUMBER is set by an in-prox pen which later leaves
proximity and sends a '0' for HID_DG_TOOLSERIALNUMBER, then only the lowest 32
bits of wacom_wac->serial[0] are actually cleared, causing the kernel to send
an MSC_SERIAL event. Since the 'input_event' function takes an 'int' as
argument, only those lowest (now-cleared) 32 bits of wacom_wac->serial[0] are
sent to userspace, causing xf86-input-wacom to ignore the event. If the event
was the final out-of-prox event, then xf86-input-wacom may remain in a state
where it believes the pen is in proximity and refuses to allow other devices
under its control (e.g. the touchscreen) to move the cursor.

It should be noted that EMR devices and devices which use both the
HID_DG_TOOLSERIALNUMBER and WACOM_HID_WD_SERIALHI usages (in that order) would
be immune to this issue. It appears only AES devices are affected.

Fixes: f85c9dc678a ("HID: wacom: generic: Support tool ID and additional tool types")
Cc: stable@vger.kernel.org
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---
 drivers/hid/wacom_wac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'drivers/hid')

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 94250c293be2..603f7fcd8df6 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -2006,7 +2006,7 @@ static void wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field
 		return;
 	case HID_DG_TOOLSERIALNUMBER:
 		wacom_wac->serial[0] = (wacom_wac->serial[0] & ~0xFFFFFFFFULL);
-		wacom_wac->serial[0] |= value;
+		wacom_wac->serial[0] |= (__u32)value;
 		return;
 	case WACOM_HID_WD_SENSE:
 		wacom_wac->hid_data.sense_state = value;
-- 
cgit v1.2.3


From 6f107fab8f18228936cd3df88a3bb6050865c2c8 Mon Sep 17 00:00:00 2001
From: Jason Gerecke <killertofu@gmail.com>
Date: Wed, 19 Apr 2017 14:47:24 -0700
Subject: HID: wacom: Override incorrect logical maximum contact identifier

It apears that devices designed around Wacom's G11 chipset (e.g. Lenovo
ThinkPad Yoga 260, Lenovo ThinkPad X1 Yoga, Dell XPS 12 9250, Dell Venue
8 Pro 5855, etc.) suffer from a common issue in their HID descriptors.
The logical maximum is not updated for the "Contact Identifier" usage,
leaving it as just "1" despite these devices being capable of tracking
far more touches.

Commit 60a221869803 began ignoring usages with out-of-range values,
causing problems for devices based on this chipset. Touches after
the first will have an out-of-range Contact Identifier, and ignoring
that usage will cause the kernel to incorrectly slot each finger's
events (along with all the knock-on userspace effects that entails).

This commit checks for these buggy descriptors and updates the maximum
where required. Prior chipsets have used "255" as the maximum (and the
G11, at least, doesn't seem to actually use IDs outside the range of
1..CONTACTMAX) so continue using this value.

Cc: stable@vger.kernel.org
Fixes: 60a221869803 ("HID: wacom: generic: add support for touchring")
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---
 drivers/hid/wacom_wac.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'drivers/hid')

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 603f7fcd8df6..c68ac65db7ff 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -2176,6 +2176,16 @@ static void wacom_wac_finger_usage_mapping(struct hid_device *hdev,
 		wacom_wac->hid_data.cc_index = field->index;
 		wacom_wac->hid_data.cc_value_index = usage->usage_index;
 		break;
+	case HID_DG_CONTACTID:
+		if ((field->logical_maximum - field->logical_minimum) < touch_max) {
+			/*
+			 * The HID descriptor for G11 sensors leaves logical
+			 * maximum set to '1' despite it being a multitouch
+			 * device. Override to a sensible number.
+			 */
+			field->logical_maximum = 255;
+		}
+		break;
 	}
 }
 
-- 
cgit v1.2.3