Patch "HID: wacom: generic: Send MSC_SERIAL and ABS_MISC when leaving prox" has been added to the 4.13-stable tree

This is a note to let you know that I've just added the patch titled

HID: wacom: generic: Send MSC_SERIAL and ABS_MISC when leaving prox

to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
hid-wacom-generic-send-msc_serial-and-abs_misc-when-leaving-prox.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jason Gerecke <[email protected]>
Date: Thu, 7 Sep 2017 17:44:12 -0700
Subject: HID: wacom: generic: Send MSC_SERIAL and ABS_MISC when leaving prox

From: Jason Gerecke <[email protected]>

commit 993f0d93f8538c15bd5c12a1a9fd74c777efea1b upstream.

The latest generation of pro devices (MobileStudio Pro, 2nd-gen Intuos Pro, Cintiq Pro) send a serial number of '0' whenever the pen is too far away for reliable communication. Userspace defines that a serial number of '0' is invalid, so we need to be careful not to actually forward this value. Additionally, since EMR ISDv4 devices do not support serial numbers or tool IDs, we'd like to not send these events if they aren't necessary.

The existing code achieves these goals by adding a check for a non-zero serial number within the wacom_wac_pen_report function. The MSC_SERIAL and ABS_MISC events are only sent if the serial number is non-zero. This code fails, however when the pen for a pro device leaves proximity. When the pen leaves prox and the tablet sends a serial of 0, wacom_wac_pen_event dutifully clears the serial number. When wacom_wac_pen_report is called, it does not send either the MSC_SERIAL of the exiting tool nor an ABS_MISC event.

This patch prevents the wacom_wac_pen_event function from clearing an already-set serial number. This ensures that we have the serial number handy when exiting proximity, but requires us to manually clear it afterwards to ensure the driver does not send stale data (e.g. when switching between AES pens that report a serial nubmer of 0 for the first few fully in-proximity packets).

---
 drivers/hid/wacom_wac.c |   27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

@@ -2141,8 +2141,10 @@ static void wacom_wac_pen_event(struct h
 		wacom_wac->hid_data.tipswitch |= value;
 		return;
 	case HID_DG_TOOLSERIALNUMBER:
-		wacom_wac->serial[0] = (wacom_wac->serial[0] & ~0xFFFFFFFFULL);
-		wacom_wac->serial[0] |= (__u32)value;
+		if (value) {
+			wacom_wac->serial[0] = (wacom_wac->serial[0] & ~0xFFFFFFFFULL);
+			wacom_wac->serial[0] |= (__u32)value;
+		}
 		return;
 	case HID_DG_TWIST:
 		/*

@@ -2156,15 +2158,17 @@ static void wacom_wac_pen_event(struct h
 		wacom_wac->hid_data.sense_state = value;
 		return;
 	case WACOM_HID_WD_SERIALHI:
-		wacom_wac->serial[0] = (wacom_wac->serial[0] & 0xFFFFFFFF);
-		wacom_wac->serial[0] |= ((__u64)value) << 32;
-		/*
-		 * Non-USI EMR devices may contain additional tool type
-		 * information here. See WACOM_HID_WD_TOOLTYPE case for
-		 * more details.
-		 */
-		if (value >> 20 == 1) {
-			wacom_wac->id[0] |= value & 0xFFFFF;
+		if (value) {
+			wacom_wac->serial[0] = (wacom_wac->serial[0] & 0xFFFFFFFF);
+			wacom_wac->serial[0] |= ((__u64)value) << 32;
+			/*
+			 * Non-USI EMR devices may contain additional tool type
+			 * information here. See WACOM_HID_WD_TOOLTYPE case for
+			 * more details.
+			 */
+			if (value >> 20 == 1) {
+				wacom_wac->id[0] |= value & 0xFFFFF;
+			}
 		}
 		return;
 	case WACOM_HID_WD_TOOLTYPE:

@@ -2279,6 +2283,7 @@ static void wacom_wac_pen_report(struct
 	if (!prox) {
 		wacom_wac->tool[0] = 0;
 		wacom_wac->id[0] = 0;
+		wacom_wac->serial[0] = 0;
 	}
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.13/hid-wacom-always-increment-hdev-refcount-within-wacom_get_hdev_data.patch queue-4.13/hid-wacom-correct-coordinate-system-of-touchring-and-pen-twist.patch queue-4.13/hid-wacom-properly-report-negative-values-from-intuos-pro-2-bluetooth.patch queue-4.13/hid-wacom-bits-shifted-too-much-for-9th-and-10th-buttons.patch queue-4.13/hid-wacom-generic-send-msc_serial-and-abs_misc-when-leaving-prox.patch queue-4.13/hid-wacom-generic-clear-abs_misc-when-tool-leaves-proximity.patch